OK, I have another one-guy-in-a-small-shop problem. I've made a bunch of rectangular frames from angle iron, but this one is a little different. The legs are much larger than my welding table. My welding table is about 4x5' and this frame is about 6x9'. I do have some flat concrete floor space available but that means no clamping to a table. This frame has to be square enough to drop over an existing wooden truck flatbed.
Ideas?
Grant Erwin