Some super advice on here already. I like what goducks said, and shelby, and especially xtech.
If you are satisfied with the way the truck sits (with rear end sag) when not using WD, you could go without WDH. But I have a hunch this is not the case.
You do seem satisfied with the way the Runner tows the TT, and you're far from the Rocky Mtns (which might change your mind), so I guess you could stick by your truck. Personally I would not worry about that TT weight, and only the heavy tongue bothers me (I have a 2008 Lexus GX470 BTW). A WDH will add to that hitch weight, too. If you want to keep the truck, the only way to go IMO is the custom frame-mount receiver fabrication. Can-Am certainly could do it, probably for top dollar unfortunately, but they do seem to know their stuff. Or look around for a welding shop with a lot of experience and reputation. And consider using the Anderson No-Sway, which is the lightest weight WDH that I know of and is IMO convenient to use; but if you do, best change out your coupler to a Bulldog or similar to be safe.
If all of this is too much hassle, another vehicle (Sequoyah perhaps?) may be in the cards.