Be careful with stick on mounts: the angle of the foil relative to the water surface when paddling the board is extremely important. Just a bit of negative angle (pointed downwards) will make paddling horrible, like dragging a boat anchor. A bit of positive angle is not as bad as it drags but also lifts the board.
So, if your board has tail rocker and you stick the mount close to the tail, the rocker will tilt the mast backwards and the results will be catastrophic. You should place it forward enough so that the wings are horizontal when paddling. The position will depend of the foil, as the mast angle to the base depends on each foil.
For the anecdote, the French foil pionneer, Bruno Andre, never realized this 10 years ago. He said in his interviews "well paddling with a foil is a chore but that's life". And when up on the foil, the board was thus tilted upwards, and the apparent wind would get under the hull and tend to raise the nose even more... and, instead of just adjusting the foil angle he... cut a hole through the board nose to let the wind pass through! This is to say that the foil angle is critical in many ways, but it is not obvious to realize this fact.