The closer you get to towing at or over your max weight, the more unpleasant your tow experience will be.
Couple things you need to look at:
1. Check the Highlander's owners manual. There are some SUV's that have a restriction on square inch or square feet of frontal area for high walled trailers, and some have restrictions on use of a weight distributing hitch.
2. Max tow weight is reduced by weight of any aftermarket accessories, passengers and cargo. If you need to use a weight distributing hitch, it will add 80 to 100 lbs of cargo weight and trailer tongue weight is also cargo weight.
3. Check the hitch receiver, it has it's own weight ratings, with and without weight distribution.
4. That trailer could have as much as 660 lbs tongue weight.
5. This statement is from the specs on that trailer "This weight reflects the rolling average unit weight for each model. Your trailer weight will vary according to optional equipment." The trailer could gain weight (maybe an air conditioner) at the factory, and it will gain weight (at least propane and battery) before it gets off the dealer lot. You should plan on that trailer being closer to it's GVWR.
