Didn't think I'd ever post in this forum - but here goes. Stopped in an used office supply store last summer and bought half a dozen used metal bookends with an idea to utilize as a chassis support. Here's ver1. A bit of tape and pretty stable. Ver2 would see a piece of 3/4" plywood (perhaps on that old office chair base) and the contraptions screwed down once placement was decided. Believe it would be very stable even with a heavy chassis. About 6" clearance on the ones I got. Pictures are self-explanatory. Tom
parts & "assembly"

In use