I broke down and bought a Tow Master Dolly and now need a bit of help in the hitch selection. Our coach is still at CW for repairs but I want to get the drop hitch purchased. What are you all using as a drop for best results of the Dolly not dragging the ramps and the butt end of the toad? I'm seeing 6, 8, and 10 inch drops all with the 5k weight rating that covers my needs. Without the coach I can't tell the drop needed on the air ride suspension - what is the drop needed?