That U-Haul hitch is only rated for 5500lbs Max even with a WDH it seems, I wouldn't get that one, check a for a Draw Tite Class 3 Hitch, I think they're rated for 6000lbs and up to 7300lbs with a WDH.
I doubt you'll find a after market hitch that attaches to both the main frame and the cross member.
Check savage yards for a OEM V8 hitch.
Agree with Auseeker, I wouldn’t go that uhaul hitch route, check for a V8 hitch from a wrecking yard or go with this one:
2005 Toyota 4Runner Trailer Hitch - Draw-Tite
Thanks guys. I am not comfortable using an aftermarket hitch either that doesn't attach at the rear crossmember, especially with the amount of weight I'm pulling.