We originally had a nice bumper mounting system but then we realized the bumpers could not go off the group with are robot. So we mounted them to the bottom of the legs. Still a pretty good system but then we ended up talking off are lifts for a better system and we really didn't have time to prepare anything else so are last system was some wood screws through the frame rail into the bumper...
It worked but it was kind of just thrown on there so next year hopefully we can get a system down good.