Once upon a time, I was able to get all our camping gear in the Sami until my wife decided she wanted her own potty.  That turned into a "bathhouse" (a combination outhouse and shower).  I'll admit I enjoy it too.  Then we ended up having to go with a larger cooler too (medical reasons).  So, now I have too much gear and I can't decide between a hitch rack, roof rack and small a trailer. I made up the attached table to help me decide but...

I like my roof rack. I built mine and it can hold way more weight than any hitch rack. Big plus is it will go anywhere that the Sammy will. A trailer or hitch rack will limit your access.

IMO It would depend on your skills and where you drive.  One could size a hitch rack to their liking.  One could make it beefy enough to support a lot of gear.  I would not do a roof rack b/c we like to drive topless more so than not.  I also dont wanna lug a cooler up high.

We have a full-size truck hitch rack we use when we need it.  Thats usually when people ride with us and we need cooler/firewood space.  It does interfere with clearance depending on where you drive though.  Again, depending on your fab skills you could make one elevated more based on your needs.  You can also wire in extra lights/pigtail if it covers your break lights.

I had picked up a hitch rack at the swap meet/flea market for $20 that was just about perfect for the back of the Tracker. It was an ATV rack. It held up to 200 pounds, fit the 2" receiver hitch, and wasn't as wide as most truck hitch racks, so it fit perfectly. It also had an offset tongue that made it ride about 6" higher than the hitch, allowing for much better departure angle. The only downside to it, and just about any hitch rack for that matter, is the fact that I had to either pull it off to get into the trunk, or at least unload it to clear the back door. This was not a problem on the X-90, though, since it has a normal trunk lid like a car.

Now depending upon what kind of riding/camping you like, I have seriously considered a small pull behind trailer and make the top a platform to place a tent or as a serious camp kitchen, for a base camp.

I have also seen single wheel trailers that work fine to get to base camp on the mtn next to that lake/pond...

I guess they all have their advantages & disadvantages - but seriously - it's going to depend on how you plan to use it.  Do you really plan on lifting a port-a-potty (ok - the op describes it as a combination outhouse & shower) up & down from a roof rack?

You also need to consider the weight - fill that green cooler on the Samurai roof with ice and you're probably pushing the limit on the Samurai - with just the cooler.

I can't speak for anybody else's. I wanted my rack to carry anything I could possibly want so I built it stout. I have stood on it several times (230lbs) and when my wife was collecting rock for her pond, went 4 wheeling with a milk crate full of rocks on top as well as some fire wood. And the green ice chest is my "small" one. The rack is supported by the rain gutter as well as bolted through the roof with plates on the inside. Have even 4X4'ed into some back country lakes with that canoe and all my gear including the trolling motor. Now a soft top would be a challenge but could be done. I have never seen a reciever rack that even approached looking strong enough to hold anything on a rough road. Not sold on the trailer thing either. I used one to haul firewood in from the woods and had it bounce off the hitch. And then there is the backing up thing in tight or off road situations. Now if you just want to haul it on the highway or mild dirt roads and leave it at a campround then anything will work. In that case I tow the Sammy behind the motorhome.

I kind of expected an answer like that.  230lbs is over the roof load limit for my GV, I have no doubt it's over the limit for the smaller Samurai.

The roof load limit has very little to do with the strength of the rack or how it's mounted - it's more about safety, and trying to prevent people from loading a vehicle so the weight is high up, affecting the center of gravity of the loaded vehicle, and making it more prone to a roll over.

By the way - bolting through the roof with plates on the inside won't improve the load capacity - the load is from the outside of the roof downwards, and having your trailer "bounce off the hitch" suggests a broken or improperly sized tow ball/coupling -  possibly an older 1-7/8 ball with the newer 50mm ISO coupling.

with a single wheel trailer backing up and trail riding is rather easy.

Still a nice looking Sammy & rack.  As he charted the pros and cons of building the roof rack, hitch, and trailer, I suspect he also considers the trails when overloading the roof rack. 
I have been considering how to build a roof rack for my 2 door tracker to haul my pontoon boat.  I just strapped it on the top around the opening and went for it, lost paint down to metal where it rode.  Now I have a lot of hp to spare, but for normal Tracks & Sammy's a roof rack has to significantly slow forward progress, because I could feel the drag and fuel mileage really took a dive.

Roof rack, No question. little weight restrictions if you do it right, no ruined angles or sagging rear end and it can hold nearly as much as the back of the samurai.

Here is my solution!

JUST ME.So don't get pissy...
 I run no back seat.
 If it doesn't fit in the back . or strap to the exo cage I don't haul it with the Zuke.
The little guy has a hard enough time pulling hills all by its self.
 Having said that. I do carry a bunch of well thought out gear into the woods.
 The cargo area in a Samurai is huge if you do a good job of loading it.
I would never even think of running a Hitch mounted rack of any kind on a Sammy for many good reasons, the least of which is that they screw up your departure angle....
 I have towed my Snow Bear trailer with the Zuke. At 80" wb. I'm not fond of the way it stops with a trailer behind it.
 I have a roof rack that attaches to my EXO. Looks very cool and is great for hauling my tents or other LIGHT LOADS.
But all the weight goes inside...LOW center of gravity is your friend.....JMHO...Boxcar...

For years I just carried what could fit in the back only.  most of my trips were the Rubicon and Fordyce.  Now I have 2 kids that want to go. So I made a trailer to tow our camping stuff.  Then I did not feel good about the weight; so I did an engine swap, Tracker hybrid rear, Celica rear disc to make the rig a little more suitable for towing. I built the trailer as light as possible and put electric steering to help out. it pulls and stops just fine.  I also have an adjustible length 3 axis tongue for different situations.  It works for me.

Great Input!  I went with a hitch rack. Pics when I get it all loaded up.