Aww, Dave, now you have me thinking about the physics of it all. Just when I thought the most painful semester of my life was going to completely go to waste...
Centripetal acceleration (acceleration towards the center of the circle, what we care about in this case) is described by the equation A = v^2 / r, where A is acceleration, v is velocity, and r is the radius of the turn. If we assume the radius of the turn is the same as the SCR of the board, which should be in the ballpark, pulling 1 G around a turn with a 12m radius means you're going about 24 mph. Pulling 2 G's puts you around 34 mph.
Obviously there are more variables here, but that should be a ballpark estimate. I can work out the angles some time, but now is not that time. :D