Reading here that Alan's truck is NOT a flex series, but a standard series Skyjacker lift, I'd say that for general trail-use, it's flexy enough. Amazing how much it was flexing two weekends ago...
Witha 5" lift, you should be able to clear 35s without problem. I'm running 315/75s on my truck (34.5") with a 3" lift, and the new BFG 35" Mud Terrains are supposedly the same size. With a 5" lift, you won't have rubbing, and will have TONS of room for flex. With 35" SSRs, be prepared for fender-damage in teh rear, as jason with his 3" suspension, and 3" body lift can attest to...
I'd stick with 5" and 35s with 4.10 gears for street use, 4.56 if you want it to be faster off the line. But with 4.10s and 35s, you're looking at being around 3.75 with teh stock size tires, and with 4.56s and 35, similar to 4.18 and stock tires.