I picked up a $15 spare tire cover to put on the spare when its on the roof, that should help some.
nice work rowhard, I have been trying something similar with a sheet of plywood and some rubber strips that lay behind the backseat. it works pretty well, thinking about doing something a little more permanent, loses all cargo space, but maintains 4 seats
I havent seen a cover that will go over a 34-35" tire, of course I am sure they exist if I were to look...
as for the spare behind the seat, mine fits, but then I cant bring my tools and whatnot. Roof or door, those are my options