I have Torklifts on a Lance 825 , sitting on a SRW GMC 2500. Torklift gives you two sets of holes to choose from. I think if you set the attachment plates directly beneath the camper attachment points you should be OK
On my dually the ties stick out slightly past 1/2 of outer tires. Fastguns should goo with some angle towards the truck frame, so measure your camper width and deduct about a foot for the spread.