If I did it again I'd use 1-1/2" square steel tubing for both cross members. I made the front one out of 1/2" x 2" steel bar which matches the thickness of the plywood liner but a thicker, stronger support would be better than a flat surface since the load can be lifted over the bar. The rear tube is reinforced with 1" square stock from the crane base to a little past the nearest bed bolt and it is very solid but the 1/2" bar isn't really stiff enough.