If it NOT 4 wheel drive a dolly will carry your Highlander very well...per the Toyota website, standard is front wheel drive.
If it is 4 wheel or all wheel drive, then you need to call Toyota again about using a dolly.
If you do use a dolly, your car will be quite happy riding up high away from possible rock strikes, saving any miles from the bottom end of the driveline, and any loss of resale value from those towed miles on the car. The dolly could be pushed under the rear overhang of your RV when not in use to save campground space, and an inexpensive tow hitch on the Highlander could be added to help move the dolly around if desired.
You might guess that I dolly tow and it works great!
Kim and Steve, Mustang LCDR (Ret), '07 Damon Outlaw #1193
I have seen gross intolerance shown in support of tolerance, Samuel Coleridge
WE LOVE OUR OUTLAW RV