After struggling to break the beads with normal methods on my 15 year old ATV tires that did not want to come off, I suddenly realized I had a near perfect setup sitting in the driveway. The stabilizer jacks on my Large travel trailer (33 ft long Jayco eagle). I shoved the tires under there, lubed the jack screw, and used a impact wrench to push them down. The jack even has imitation curve on it's foot pads that fit the 12" rims. Boy were they stuck on. Even had bits of rubber rip away and stay on the rim. They must have been glued or something.

Four tires took all of about 30 minutes. Easiest bead breaking I've ever done.

More about my Sportsman Here: My sportsman history





Anyway, thought I would pass this along. I'm sure someone has figured this out before, but since I can be kind of dense at times, you never know.

 

I've done the same, but with a bottle jack under my trailer hitch on my truck.
I like your idea more, as it's permanently mounted to the trailer, so you wouldn't have to fumble around holding the jack in place. Thanks for sharing.