31's are the largest tire you can fit stock. Therefore the only reason you haven't rubbed (noticeably) yet is because you haven't wheeled it yet.
Best bb in my opinion is some 2" spacers, good shocks that are 2" longer than stock, some 2" bumpstop extensions, and 31x10.5 tires. It'll look good and give you a little more ground clearance but avoid driveline troubles and retain stock wheel travel (as long as you get longer shocks).
OME 2.5" coils and Nitro Shocks, Metalcloak front track bar, JKS Quick discos, 33x12.50 Goodyear MTR's w/Kevlar, 15x8 Pacer wheels, thedirtworx rear tire carrier