this is an old thread and the op has oved on....but the info could be helpful for others...so I will chime in too.
I pulled a 22 foot SJX boat with an inboard, and loaded for a week of camping,, and pulled it for about 800 miles, round trip , including hills, with my 2000 4runner. It had the TBU at the time. I dont think it was a very good idea, I did not like the way it drove. It was a long planned out trip and the rig that was supposed to pull it was in the shop. They are not as heavy of a boat...but I still did not like it. Ive pulled many other things with my 4runner....smaller/lighter things....with no worries
SJX Jet Boat Home Page - SJX Jet Boats
However my sons 2016 v6 taco pulls that boat with no issues and feels fine driving. But side note , sold that boat yesterday and going smaller with an outboard.