D-Rat just does desert running, no mud or stuff that makes shocks corrode. The only place I would run boots is for high speed desert stuff, to protect the shafts from rocks or whatnot.
I would check out a motorcycle store and see if you can find some boots that are meant for dirt bike forks. Those come in some pretty long travel versions, maybe you can find something that would work. That or see if Rancho makes some long ones for the real long shocks they make, like the 15" travel 9000s.