Get one with wider wheel stance and bigger tires, hand held throttle.. Or make one buy the motor and cable build the platform. The motor is the size of a chain saw motor in fact you can use one to make one of these things.

http://stuccu.com/s/Gas+Powered+Skateboard?duk=gas%2Bpowered%2Bskateboard&keyword=%2Bgas%20%2Bpowered%20%2Bskateboard&matchtype=e&querystring=gas%20powered%20skateboards&netid=2&aaid=531c9197abacf029e072511c&oid=28550540543&caid=531c9197abacf029e072510a&device=c

WHOLESALE PRICING

http://www.alibaba.com/showroom/gas-powered-skateboard.html