On a diverted note about tying the bike down, I would suggest one of 2 things. When I have trailered motorcycles, I blocked up under the engine so the frame rested directly on a 2X4. This way the bike was held solid and would not move around. Straps went up to the triple clamps.

When I built the carrier for the PC800, I welded 2 brackets that went up to the crash bar. In my particular case, I just unbolt my HWY boards, and bolt the bike in place. 2 bolts hold the bike, and it is very quick to load and secure. no straps needed. Not sure what kind of bike you are carrying, but I would suggest welding some tabs to the frame and then welding braces from the carrier to the tabs, so the bike can be bolted in. It makes it sooo much more secure, and quick to load and unload. I find the concept of straps too temporary for day in and day out use.
