I can weigh a 7.2FX tomorrow since it's a point of interest. I assume you'd take one of the larger sizes?

At 285 pounds, you may fatigue the spokes in the rear wheel sufficiently to begin breaking them after 1-2 years if you ride quite a bit. If the shop has a good wheelbuilder, you could ask them for a quote on rebuilding the rear wheel with top-quality spokes, which you can expect to far outlast the OEM ones. Or you can just cross that bridge when you come to it.