Another fat boy here. I'm 6'3" and weigh in close to 4 bills. I've worn shoulder rigs with autos (Glocks mostly) but never a wheel gun. The only bad thing about a shoulder rig is being able to reach around your kiester to get to it.
You didn't say what wheelie you prefer to tote, but I'm guessing it's a 4 inch K or L frame...right? You might try a crossdraw holster. Galco makes their "Phoenix" which looks like a damn fine rig.
I would prefer it over a shoulder rig.