I have towed trailers of similar size and weight for over 140,000 miles with an '08 Highlander, and it did well. Only on long grades at high elevations I'd have to gear down to 3rd and take the climb at about 40-45 mph, but otherwise 270 HP was plenty. So if you get a pickup with a V6 you should be good. Even so, a V8 could put a grin on your face at times like that, as you would not be slowed down much. A RAM 1500 with Hemi would be downright fun on the long, steep climbs.
That said, you have an excellent vehicle right now. Don't be afraid to try it out. I believe the weakest link in the drive train is the rear end (due to the relatively small gears that came with the 4 cyl), but if you ever did mess them up it's not hard to replace them with a larger gear set, and get right back to towing.