I built one out of a 6x6 tube that is about 12'. Then made an insert sleve for a 4x4x3/8 tube inside with about a 7' cylinder to extend it. This was built for a 5 ton SS and it's worked great, I've set a bunch of trusses with it on smaller & lower bldgs. It's great for pole bldgs. as you don't need the reach because you can drive into it. With only a 2x3 tube and not being familiar with your tractor size or loader, I'd be conservative and cut it in half (no extension) and join them together at the hook end and use a cable for the top brace to make a triangle shaped pole that all 3 points coming together at the hook. The 2x3's joined togher should work well for the lower (compression load) legs with the cable, prolly 3/8 min. for the top (tensioned load) leg.