We're Class A owners rather than TT. On most motorhomes the parking brake works on the back wheels. Don't know how TT's are configured.
We make it a rule NEVER to lift the back wheels off the ground when levelling. If a site is that far out of level, we either ask fo another site or we turn the rig around and raise the front. A typical case is our daughter's house, where we stay regularly. The grade on their driveway requires to front wheels of the rig to be about 15" off the ground. We need a 2-step ladder to reach the bottom step of our retractable steps!
Once we're set up it isn't a problem. The rig is level, the fridge doesn't have a problem, we don't keep rolling out of bed! We almost need crampons and ice-picks to get to the door!