Once again, obviously.

But thanks for the insight.
Did he definitively say 2.5s are out of the question? No. I said "if you can swing for 2.5s," and the fact that he asked about them tells me that they could be an option if they are worth it. So my question is valid. There are certain things that are worth spending a little extra on the first time, to avoid having to pay more a second time. In desert trucks, shocks are one of them.
How long in the future would the upgrade to coilovers be? How often will you be actually using the truck offroad? If coilovers are in your future, then wanting to push the truck harder seems to be a good possibility. Both 2.0s and 2.5s can be rebuilt and sold used for a good amount, so even if you plan to upgrade, you can still make some money back with either one, so don't count this first pair of shocks as a total loss. If it's only going to be a year and a handful of trips, then a 2.0 with the right valving would be sufficient. If it will realistically be 3+ years going on trips every month or two, that's a long time to go with an insufficient setup.
With my 2.0s, although my truck is A-arm, the rear is the same as yours, and they are burning after a good 10 minutes. For example, Colin, think of the pole line road along 86 going from N. Marina to the gas station. That road isn't incredibly rough. My rears are also valved pretty heavy, and for the fronts I started out with the heaviest possible valving, and then had to add even more shims and it's still soft.
IZ, usually with coil springs travel is more limited than with coilovers, and an 8" or 10" shock is typically used, often without an engine cage/shock tower. With coilovers, an engine cage/shock tower should definitely be used, and coilovers on these trucks are typically 12" or 14", so that's why he said he'd need to get new shocks at the point anyway.