I'd go with the 235's. The difference in drivability between the two isn't all that much, but if you need to replace a tire in an emergency situation 235's are much more common than the 215 is going to be. That way if you had to get a used tire in a hole in the wall sort of place that's not an offroad design just to make it home you're much better off. A lot of small trucks use the 235s. Same reason I'll probably stay with 31x10.50's instead of 32x9.50's or 33s. 31x10.50's are a dime a dozen comparatively.
Either one should fit ok on your wheels even if they're stock ones. Plus since you do offroad it a little bit you'll gain a smidge more ground clearance with the 235's which isn't a bad thing. Heck I'm getting close to 11 inches of clearance on mine just from throwing the 31's on it without a suspension lift installed yet.
Absolute worst case you could get the U.S. wheel steel rims from summit racing for about 40 bucks each for 15x7's and summit also has free shipping which on a set of wheels probably saves you 25 bucks right there. Sure they're not the greatest rims in the world but they do the job. There's also the American Racing ones and so on.
I think the ones I have are 2 1/2" or so backspacing which is just the default setup for the 5 on 5.5 lug pattern version of em. As it is now, I just barely rub the frame rails with the 31's at full lock on the steering. With the 235s you wouldn't run into this though since I had 235's on those rims before and it definitely wasn't a problem.
I see you're in vegas which is probably a big enough city to have some used wheel shops around, might be worth a look although I found here in Phoenix that the used ones were generally selling for 25 bucks or so per wheel for used steel oem or otherwise. I figured screw it and just bought new ones.
Absolute worst case, without a body lift but with the spring spacers you have you still might run into some rubbing at the back of the front fender with the wheels turned when the outer edge of the tread is closest to the back of the fender. That's easily fixed with a sawzall or snips, or if it's just barely touching a bit of assistance from a hammer should do the trick and you can do it so that it isn't visible on the cosmetic part of the fender. (had to do it for my 31's since I've only got the body lift for now.)
Oh and Van, with the auto even on 31's it's not all that bad, plus there's a nice trade off of lower engine RPM's on the freeway. Granted I've also got the Hawk Suzuki Cam, the head and intake manifold portmatched to the gasket, .030 over pistons, .020 milled off the head, and a header and 2" mandrel bent exhaust with a straight through muffler. I've been tempted to put the factory size tires and wheels on it just to see how it is since I've got all that finished but figure it'd look pretty lame with the body lift and no bumper covers. Seriously though it's not all that bad. (still wish I could swap it for a 5 speed though since I friggin hate automatics). The lower rear end gearing is mostly there so the 1:1 ratio of 3rd gear is about the same as when you're in 5th with the manual. (works out to about a 4.40:1 final drive ratio with the manual vs the 4.62 with the auto)
So to conclude: get the 235's and if you can possibly spring the extra 200 bucks or so get some 15x7's too.
