Tow hitch with a rollpan?

[abadsvt]

I am building my truck for show (not to win awards but being able to enter and have fun!) but also i would like to tow my boat. I plan on puting the gas tank in the rear like everyone else does but i wanted to make a hide a way hitch behind the license plate. My question is I do not have the bed which mean i don't have the rollpan yet also. I do have the stock bumper. Can i use the stock bumper for alignment of the hitch so it is center of the license plate on the rollpan? Does the rollpan bolt onto the frame or does it just weld to the back of the bed? I am going to powdercoat the frame so i am trying to address everything ahead of time. Am i going to need the bed with the rollpan installed to get it correct or does anyone have an idea on how far the rollpan is away from the frame? I do have the stock stepside bed. Could i use that for an idea on where the rollpan would sit on the fleetside? I think i confused my self . Anyways thank ahead of time. Josh