The Highlander is a CUV
First gen was based on the Camery
Second and later gen is based on the Sienna Mini Van
Just think of towing with a Camery if 1st Gen, and towing with a Sienna Mini Van if newer
Both monocoque/unibody, so WD Hitch system is normally no recommended (understand any OEM's 'recommendation' means no warranty if you do NOT follow their 'recommendation')
As Barney said, check your configuration and note that the MTWR is *NOT* an absolute. Meaning it depends on the configuration and loading of the TV. Again, check your glove box manual...as their should be an info page on towing listing the REDUCTION in MTWR with each passenger loaded into the TV
