It may be possible to make a device that reverses it automatically, I would use an accelerometer rather than a tilt switch as should give you more control as to when it reverses, then use an arduino mini or something to take the signal from the rx and just reverse it and send it out to the escs. I imagine you would need a small delay between when it first sense it has flipped over during which tk continues to check (ie has to be upside down for say 1 second before to switches the controls to avoid false positives)

Probably a lot more hassle than its worth but it is an option.