Depending on the direction of the slope and the make of the generator, the low oil sensor may decide there is not oil and refuse to allow the generator to run.
The fridge almost certainly will not work on that slope. Worse, you may possibly destroy the cooling DO NOT DO IT.
2011 Silverado 2500HD Duramax, 4x4, crew cab, long bed
Palomino Puma 253-FBS, 27' 5th wheel
1994 19' Class B on Chevy chassis