I agree about Carlisles - I don't know Maxxis. We will see about the Kenda tires - they are new to me. But at least  they are rated at 1/2 again the load rating as the Carlisles so hopefully they will last a bit longer. We will have two spares now. 
I think what I am going to do is swap out the axle for a leaf spring axle (when I get to a place we can do this) and raise the body a bit higher off the axle so there is room for 13's or possibly even 14's. That will at least give me a lot more options and should allow for a better tire than the 12's.
The current axle is a torsion axle but the frame looks like it should be no problem to swap out. Or possibly  just block and lift this axle.
I like the idea of using LT tires.
Thanks