EDIT on second thought i'll just get some cheaper stamped steel ones and beef up the hell out of them
Probably your best bet. Either that, or tig weld yourself something like this cut out of steel at least a quarter inch in thickness:
Welded correctly, that design would probably hold a C-body up - with another C-body on top of it.
EDIT: Forgot to add guides and a stopper:
The plastic ones work well if used cautiously.
Therein lies the crux of the problem. Any tool that is critical enough to be the only thing between survival and serious injury (or death) shouldn't have to be used with the feeling that the tool is a point of primary failure. Of course, anyone raising a car through ANY means should use caution, but there should be no doubt about the structural integrity of the tools being used - especially ramps, wherein failure is not mechanical.
Granted, I don't expect the average car ramps to hold a 3/4 ton truck, but I do expect them to be built entirely safe enough that any car - including a C-body or old Lincoln Continental (essentially anything up to the 5,000 pound range) - can be driven up onto it with assurance of safety (assuming level, concrete ground, of course).
It's not that much to ask, really - but there are too many people out there willing to accept mediocrity at a cheap price that it is next to impossible to find ANY safe ramps for sale at any major retailer.
As for the plastic ones - for a few extra dollars in ABS plastic shot into a mold, Rhino/Blitz could be casting these gussets solid across the width of the ramps, or at least with a connector at the bottom forming a circular hole without introducing a stress riser like this U shape:
...but no. Someone's life has to be put on the line for a few bucks. Disgusting.
I'll admit to owning a Harbor Freight manual tire remover (despite the embarrassment - only HF tool I've ever knuckled under and bought), but at least that thing isn't supporting two tons over my head.
-Kurt
