A friend needed to lower his TT a few inches to be able to get it into his barn.
He made 4 steel discs (using 1 inch thick steel plate) to replace the tires on the TT. He would jack up the TT, remove the 4 tires and wheels and replace them with the steel discs, then back the trailer into the barn. He'd leave the discs on until he pulled the TT out of the barn.
He made the discs just large enough to provide ground clearance but lower the TT enough to get it under the door. It worked great but what a noise it would make against the concrete floor of the barn.