Same here. My blower is fine going forwards in not-yet-frozen gravel, (shoes down all the way of course) but as soon as I turn, the inside edge pulls gravel into the blower and you know what happens.
It took me a few tries, but I just did a combination of:
-hmmm, I can let that 1-2" of snow sit there and we'll just drive on it.
-waiting
-try to go as straight as possible when you do blow
-raise the blower up. (FEL stick/hydraulics) This "works" to eliminate most gravel from getting in, but unless your driveway is dead flat (who's is?) the blower will naturally move up and down with the curves and bumps that the tractors 4-wheels will encounter, rather than the blower riding on the shoes like normal.
One thing I have NOT done, is custom fit some biggie WHEELS (like you'd see on the front of a ZT mower etc) and fix them somehow onto the blower. This mod has promise, but lotsa work. Especially for my particular blower which has bracing in all the wrong spots for mods. (BX2830 blower on a BX2380)