hard mounted Wilson means drilling/cutting a hole in roof.
I have the Wilson 5,000. Works awesome, but sticks way up. Although it is magnetic and you can leave the base magneticly stuck to the roof and unscrew the whip whenever clearance permits.
One good option would be to mount one of those thick short whip antena'a to the rear of your VX down low by the rear door. Would never worry about clearing anything.
when mounting on roof I believe you should mount closer to the center of the VX.