The underside is covered with "Darco," which is common for RVs. There's fiberglass in the walls, but they're only maybe 1 1/4" thick, so maybe R5? A radiant barrier (basically aluminized mylar) is part of the "SE" package for the 177, I assume it's an option on other models. Radiant barriers roughly add 50% to the R value, so maybe R8 with it.
I doubt the roof is different than the sides, and the floor is just 5/8 OSB (?) and the Darco, I think - so not much.
They're not made to be all season campers, even without water.
I'm in the middle of putting Coroplast underneath behind the wheels, to provide a bit more protection from water and stuff the tires kick up.