Transaxle fluid change, car slightly tilted

Walked past a fellow working on his car this morning who had "solved" the tilt problem by aiming his car downhill and propping up each ramp under a front wheel with a short piece of 2x6 perpendicular to the ramp. The boards were flat on the concrete. Unfortunately the ramps were entirely supported at two points where the edge of that wood contacted the two sides of the plastic ramp. Also I suppose a little by the line at the shallow end of the ramp which was on the concrete. The back wheels were chocked. If I had to design a method to break plastic car ramps using only the weight of a car and two pieces of wood, it would have been this. The pressure at the wood/plastic contact point must be huge. Rough drawing of just the front wheel: