Springer wars sounds like fun.
Might be worth having a weight limit as well, just like robot wars.
It is worth someone doing a quick tutorial on how to enclose all the electrics in a butty box, or otherwise waterproof them, to save them.
Will you allow flame throwers, blow torches? It may be an advantage so strong that it becomes the only real weapon of choice, and thus defeats the fun.
An alternative, if some think Springer Wars too destructive, labour lost etc.
Springer jousting. Just need to knock the superstructure off of the opponent. With a standard for size and fixing of superstructure (or not fixed down) and standard for lance. Superstructure can have a uniform shape but then be painted however.
Just a thought.