You should have no problem mounting a Thule box. My name is Corey and I work at Sports Rack www.sportsrack.com and we have mounted these boxes before. I personaly own the EX blue. I will have pictures soon of my custom rack on my E. I have bypassed the factory rack and have installed tracks from Yakima. I am able to carry baskets, bikes, boxes, and kayaks. You can contact me with any interier and exterier rack questions for the E any time.