If your into drifting, trail riding and just general duning a 20x10x10, 9 paddle extreme will work much better than the V paddles. But if you want to be doing the tree shots by the water, or drag racing I would suggest a 22x11x8, 8 or 9 paddle extreme. Preferably a bead to bead buff (the tire is ground down to eliminate weight.) But you're going to be spending some coin on them. I don't know what your budget is, but if this is a one time dune trip, I would say go with a used set of 20x10x10s.
For fronts your dirt tires will work.
Gearing will have to do with what type of riding you'll be doing. As long as your not running a ton of gear, it'll probably work.