thats some serious mod, a lot of risk for almost no return.
cheap and dirty way for a geek to do it: bicycle computer with the sensor coupled to the passenger side transmission (the part that doesn't move with the suspension).
I achieved to take mine to 85Km/h on a very steep incline

so it doesn't seem to have a limit and you could avoid speed cams with that.
the accuracy increases a lot if you glue it to a rim, and have the sender in the caliper for instance.