I like that body on whatever rig that is, looks kinda like that monster truck that’s supposed to be an earth Vader helmet or something. I can’t remember what the name of it is.
What is that body?
I did this same thing, yet used cardboard boxes and spray foam. I painted it with some grays and browns, then used a clear sealer for abrasion resistance. Something like flex seal spray would work. Yours looks good, it will be fun.