it might be a crazy idea....
but how about some sort of a level switch ??
you know.... like pinball has those level switches for tilting...
when the panel is not in place, the panel is kinda like tilted or upside down.... thus turning the switch off....
but when you rotate it to place, then it'll be levelled, and thus turning it ON !!!....
up to my knowledge, those level switches contains mercury... (which might not be a healthy thing when broken...)
are there any alternatives ?? safer kind of switches of that type ??
if this is good, then you don't need switches at all !!... just roll it in place and when its level enough, will turn it on automatically.... roll it out and off it goes.... haaaa haaa haaa haa.... what a genius idea.....

(ok.... getting carried away....)