Off the top of my head, if you have to alter it, I'm not sure it's any easier than building one from scratch. It doesn't have facility for pivots at the "wheel" end.
I don't know your fab skills, but I'd be more comfortable using steel. I'm also curious about whether a bike part designed to cope mostly with twisting loads on a 400-lb bike is going to want to put up with dead-sideways forces from a car.
And to point out the obvious, they H-arms and not triangulated. That cross-brace would be better as a diagonal in your application...
Not that it couldn't work, just listing the concerns that spring immediately to mind.
