I have a 93 Tracker with a BDS 2". I was wondering if I would have any issues with adding 1" spacers to these coils. i.e. drive shaft ext. or diff. drop

thats a good question that i wished I knew the answer to have you checked the archives yet, I would but i can never find anything there.

i put 1" spring spacers ontop of my calmini 3" kit.
never had any probs with it.

You will run into problems with strut length, camber angle, rear top mount ball joint, probably brake lines, prop length and a few other things too.
At the very least you should fit strut spacers, camber bolts and a rear diff spacer. Front brake lines can be relocated. Not sure about the rear I have braided lines.

Flipping your top strut mount will give your struts the 1 inche that you lost with the coil spacers

i put 1" spring spacers ontop of my calmini 3" kit.
never had any probs with it.

Yeah I'm considering doing that, the Calmini package is more comprehensive than others.  A BDS 2" kit + 1" spacers is  like a Calmini 3" without extended drop link brackets, trailing arms, v-bar and control arms.

My opinion is the Calmini 3" kit can adapt to 4" without putting additional stress on the replacement arms/brackets (recomend RRO's driveshaft extension).  However the BDS 2" kit is already pushing your stock arms/brackets and drivetrain, if you add a inch spacer, at 3" Calmini decided that droping the front axle, and extending the trailing arms to the rear axle was neccesary to prevent dammage to your factory components.

i think if you won't drive to hard it would be ok 

i'm running 2 1/4" coil spacers in the front and it is fine.