I regularly tow 6000-8000 lbs behind my TC. Yes, get the SuperHitch with SuperTruss extension and use a WDH. Your biggest concern will be rear axle weight and the capacity of your rear rims and tires - I run 19.5" wheels due to my trailer tongue weight on an extension.
Expect the enclosed trailer to weigh around 3000 lbs empty, so you may want to look at trailers that have a 10,000 lb rating instead of the cheaper 7,000 lb versions. I went with drop torsion axles for a better and lower ride. Some cars will have issue with break over angle between load floor and ramp with standard height trailers. It will be difficult to open your door once inside unless you have a man/escape door or the left side of the trailer over the wheel wells - Look for this feature when trailer shopping.
I prefer to use wheel nets to secure vehicles instead of anchoring the chassis. Make sure you have enough tie down points on the floor to anchor your Prius and quad.