Are you going to be using a Thick Wire/Cord throttle like you use in the videos if so why not use a remote throttle like exskate/altered skateboards with it maybe connected to a wristband so yo don't lose it if you fall and a switch that can limt the max speed between 10,20, and 30 mph check out this website for an idea of what i am thinking of:
http://www.alteredelectricskateboards.com/actionvideos.htm
check out all the videos not just the first one because some go into more details than others thanks for listening