Sand will put a higher load on your engine so I would run a larger main jet assuming you were jetted correctly for trail riding. If you are running a #7 plug you may want to consider a #8.
I would also change gearing If your stock to something like 13/50 or 12/47.
Not sure what the recommended pressure is for a paddle tire but I would guess 8-10lbs would be good for sand.
You also may want to stiffen your suspenders to improve handling.