I installed the Curt hitch (#11805) on my wagon just last week. It attaches to the body between the bumper and the frame - they supply some heftier bolts to replace the ones that hold the bumper on.
It's a massive pain in the butt; the bolts are as bit bigger than the stock ones and you will probably have to dill the holes out a bit bigger (I did). This was compounded by the fact that the bolts (welded together in pairs to a steel plate) weren't exactly parallel; I had to hammer the plate a bit to straighten them out so they'd align properly with the holes.
Getting the new bolts in place on the passenger side is practically impossible - you have to reach through the rear windshield washer well and twist your fingers through a small hole under there to reach the holes the bolts go through. I barely managed it after 40 minutes of cursing
. If you have kids or know anyone with smaller hands it might be a lot easier for them, though. On the driver's side (spare tire well), the steel plate the two bolts were welded to was too big to fit into the hole (there's a lip at the top) and I had to cut a few millimeters off the top.
There's also an additional bar on the right and left sides that attach the hitch to the underbody (you have to drill holes through the floor of the spare tire well on the driver's side and the rear windshield washer well on the other) but I don't plan on pulling anything heavy so I left those off.
All in all it seems pretty solid. I haven't used it yet but I don't envision any problems. Once you get past the painful installation process it looks pretty sweet.