1) Place the rack case on the floor with the cab on top of it. This would be a brilliant idea except you have to reach waaaaaay down to the floor to plug in and adjust your controls

. Plus, bass cabinets sound better coupled to the floor instead of elevated.
2) Borrow a chair from the venue and set the rack on the chair right next to your cabinet. That would be a brilliant idea except the furniture in most clubs is way dorky looking and even if it wasn't, it would still look nacho cheesy to have your gear sitting on a chair borrowed from the club.
3) Bring a piece of 1" to 2" thick, dark gray or black foam rubber that is the same size as your rack and put it in between.
4) Don't worry about the little dents. Life will deal many many challenges, problems, and disappointments that will make the dents so insignificant you will wonder why you ever invested the concern in those little dents.
-b