For reference, I put 140,000 towing miles (out of 185k total) on a Toyota Highlander which had similar output V6 and 5-speed auto. Mostly towing my previous 6x12 enclosed cargo trailer for work, around 2,500-3,000 lbs loaded. My TT was 2700 lbs loaded, 7' wide by 100" high, and boxy; I towed it through the Rockies several times. The Highlander did fine towing at 60 mph; 65 was pushing it if there was a headwind or a decent uphill climb. At highway speed, wind resistance is a bigger factor than weight.
When climbing a grade you usually have to slow down anyway, so weight becomes the bigger factor there. The trailers you're looking at are somewhat more aerodynamic than the boxy conventional trailers. Less wind resistance means less strain on the drive train. Unless you want to drive fast, you should be fine with the JGC V6. Expect likely 15-16 mpg at 60 mph or so, versus more like 11-12 mpg that you'd get with a conventional TT; that should tell you something about the aero shape of molded fiberglass trailers. You can find a few data points in this table I used to maintain for another RV forum:
tow vehicles and FG trailers stats