BaHaHa, I love it!
Let us know how it goes running with the big boys. I bet it will raise some eyebrows with it's lighter weight and ATV tires. Despite being FWD it should pull along quite well in the sloppy stuff, as long as you don't stop. Actually with your mods it should launch itself pretty well. Man that thing looks like fun.
Did you add any recovery points? Do you know the current vehicle weight?
I think the welded diff should be more than OK for your intended purpose. It's not like a fully locked 4x4 and should handle much better than a locked RWD vehicle.
I had a B2200 with poor-mans traction control (handbrake to each rear wheel) and while it definitely helped getting unstuck it wasn't that easy to use on the fly and would not recommend it.
Talking about hand brakes, Have you considered rigging a brake to lock the rear tires for super-sharp turns like some rockcrawlers with a rear-disconnect?
Anyway love your project and have fun on the trails.
Try not to get run over
