Towing with the XJ

I'll be towing a small U-haul (5x8) down to school with me this year and have a question as I've never really towed anything before...

My XJ has an RE 4.5 in lift and also a Detours Slimline rear bumper with the hitch built into it, so I'm not sure of how much drop to get on the ball mount... Any ideas?

I ran a 5 1/2"(I think, it's the one with the most drop at Wally World) drop hitch on mine with a 5.5" lift and it still sat high. So you should be just about right running one that size. They're like 20 bucks at Walmart.

tractor supply sells adjustable ball mounts. thats probably your safest beat