Why not use a rack with a back pan that can be bolted to the wall? The rack would only need one or two casters at the front corner or, just mount it to the wall and leave the casters off- I did this with an Atlas rack about ten years ago and it has worked great. That floor is more uneven, too- no problems with acess and it can be hung from either side.
My mechanic told me, "I couldn't repair your brakes, so I made your horn louder."
