I agree that the uptravel is usually not as desirable for crawling. And your axle will still pivot around a bottomed out shock. I think I would go with the final option of a longer shock....if that is the only option. You could also move your lower shock mount if your handy to help tweak the numbers. I purchased some mounts from one of the vendors, and modified it to fit near the original location.
Also I strongly encourage some type of spring retainer. I tried to go with out them and lost a spring a couple times....So I just welded some "tabs" that hold my springs to the rear axle...I used some scrap 1"x3" metal cut 1" wide and then cut this into two sections to form two "J" hooks. I put two per spring, 180 deg apart. A quick and dirty diagram shown below. Sorry if this is confusing, there is probably a better solution.
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I don't really have any good pics of this cheap fix, but you can slightly see one in the picture below (driver side). When I flex it out the spring does drop off the "pad" as seen on the passenger side, but never gets below the
passenger side. bumpstop.

Ultimately you do not want your shocks being the limiting strap or a bumpstop, because it shortens there life span. I've also debated getting longer springs, but I can't seem to justify it. Others are welcome to chime in.
<edited wording with the strikethrough>