I never saw a real burro without a flat car behind it. (might have been the same one..?) ...Maybe put it in a gondola? A load to hide the board?
An unplugable teather with a mini-headphone plug; jack in the burro? (so it could instantly return to conventional if unplugged)
Neat idea.
Even if you had to "change gears" manually , the newly chosen function would work from the controller at least. (finally...what I see as a really good reason for a remote. Changing those gears and walking back to a throttle, walk again to change gear, walk, power, walk, gear, walk..... it gets old kinda fast eh? 
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