Originally Posted by RachelW
We had the hitch put on the back of the Scamp
when we ordered ours, tried bikes on it once and had so much extra sway that we said never again.
We also had a factory receiver installed. RachelW is correct - the extra weight
aft does contribute to sway. I found it occasionally noticeable but not excessive, and we mitigated the problem by putting all of our heavier gear forward inside the trailer.
Another issue with the rear-mounted bike racks you should be aware of is bouncing. A trailer will bounce a lot more than a car, and the effect is magnified at the rear. That puts a lot of peak stresses on the rack, receiver, and the frame of the trailer (which is not known for being heavy duty!). It also means the bikes will bang into each other. Ours are inexpensive, lightweight bikes, and I have learned where to put padding. If you plan to spend much time on unpaved roads, this might be a deal-breaker.
In short, a rear bike rack is possible, but definitely not ideal.
Floyd's rig is clever and good for stability, but could overload the tongue for some TVs (such as the OP's Subie). Donna's suggestion is ideal for aerodynamics, security, and towing stability (and inexpensive, too), but I like being able to use the interior of the trailer en route. A roof rack system on the TV is another option - stable and secure, but bad for aerodynamics, pricey, and a pain to load/unload.
Lots of choices, none perfect, I'm afraid.