The real question is, how strong does the ramp that I'm going to drive two wheels up on to tip the roof to the sun need to be? Can I build it out of 2x4s and 3/

The real question is, how strong does the ramp that I'm going to drive two wheels up on to tip the roof to the sun need to be? Can I build it out of 2x4s and 3/4" plywood and how far apart do the offsets need to be? Is it OK to leave a car parked for long periods at a 30 degree angle?