I think after you try the tires you'll find that 25 lbs is still pretty stiff. I would suggest trying them at 25 and at 15 and notice the difference in traction and handling on rough dirt roads.
If you are using those internal beadlocks you could actually run at 0 psi if for some reason you chose to. As for the tire sealant, I'm not sure about that brand, but some brands will cause aluminum oxide to form inside the rims making them brittle. I'd also find out from staun if tire goop will hurt the internal locks.
just thoughts
By the way, is this thing gonna be able to shift in and out of 4 Lo? or will you just leave it in 4 Lo? With a top speed of 40 it wouldn't be out of the question.
Most importantly,, when you run this puppy across the desert, let me know. I'd reallly like to watch.
Andy