[Michael Corsetto]

Drop in bumpers with bolts sliding into slots in L bracket aluminum, fastening with wing nuts? Design courtesy of 1114's 2008 robot. If you factor in the time it takes to set up the rivet remover tool (whatever that may be), we might have you beat?

I'd like to see the rivet method in action...

I'm pretty sure any of the previously mentioned methods will be under 10 minutes, but if this competition results in someone having to kiss a pig again, let the games begin!