5" of backspace you mean? 5" of offset would be pretty crazy, and totally different than 5" of backspace.
Depends. If the rim is at least 17" in diameter, then yes, a wheel with a bit over 5" of backspace will fit in the front. If it's 15" or smaller not a chance. In the back it will depend on the rear axle, if it's an 8 3/4 with the large 5x4.5" bolt pattern axles you'll probably need a small spacer if the springs are in the stock location. If it's anything else you'll need a fairly large spacer, probably over a 1/4" thick.