Problem that I can see is that (for example) if you get enough 1 and 4 combinations, regardless of the MOF, you can eventually hit the target hex even though you supposedly missed. Ex.: 1, 1, 4, 1, 4, 4

I think you should require that, "after rolling the first die, determine the opposite side from this roll. All numbers corresponding to this roll must be re-rolled."

i.e.: MOF is 3. You get 6, 6-sided dice to determine the drift. On the first roll, you roll a 2. Rolls opposite of this should be a 5.

2, 3, 1, 2, 5, (re-roll), 6, 6

Hits 3 hexes away from the target.