one thought is that you might be able to use two different engines- if small enough- to power it proficiently. the problem is, after you have the motor taking up the space, the air cushion and suspension system are toast. the suspension might take half of the rollerblade itself.
Merged post follows:
Consecutive posts merged
if you connect the drill batteries to a, lets say a small car battery, u would have a large amount of time. leaving room for the safety issues of the air cushion an suspension. Also, having that load cell would probably be a better indication of how much power will be used