IMHO, the answer is in your statement. You bought it NEW. The condition that it's in is unacceptable for proper use. Show the dealer the page in the TT manual. and the refer manual that says that you should be level to properly operate, and have the dealer fix it, if it's a problem. That said, the refer may have a floor that's slightly sloped by design.
There's not a lot of "adjustment" room in my refer wall opening, so I'm fairly sure that if I had to modify mine, it would be a "big" job....
2014 RAM 2500 Laramie 4x4 Quad Cab w/Cummins Turbo Diesel, 2009 Rockwood 2607, and 3 'yaks!
300W of Suntech Solar, a Rogue MPT-3024 Controller, and a Xantrex PW2000 Inverter