It''s interesting, but a 7,000 pound XV-JP can be as steady, stable and safe-feeling as a more normal highly-built Wrangler (which can easily hit 5K). The tires have more than enough capability, well over 3,000 pounds each, and the current heavy-duty suspension (nth degree; now AEVs) has plenty of reserve. That said, however, the original configuration, with Goodyear Mud-Terrains and a more-flexy TeraFlex suspension was not as inspiring, though it never felt outright dangerous. But the current configuration has no vices at all.
As far as the "recertification," I'm not how they would do that, as I'm not sure there's anything related to weight that was ever certified in the first place on a Wrangler, Tacoma or so on. I think it's a matter of having the individual components up to the task. I've (remarkably/embarrassingly) had a 6,000 pound Tacoma, a 7,000 pound Land Cruiser 80, and this 7,000 pound Wrangler, and all have been more than up to the task of carrying the weight.
Another thing to consider is that by selecting the Tacoma, you've picked out the truck with just about the least payload available of the alternatives. If you were, for example, to use a new Ford F-150, the payload would be close to double that. Even the Colorado is a couple hundred pounds better. And I'd guess anything above 2K would do be enough for a credible cabin, though I suspect payload, like space, would get used up if you have it available.
with an XP cube. Good news is my wife likes the XP and Uro-camper designs so there is hope!