Just came back from a decent towing session down south in the work AU Sedan (4L, 6-Banger, 225k kms) towed my FC RX7 so nothing crazy. Ate some fuel with the weight in the back but didn't mind the trip home with only the trailer and no car on it. In saying that I wouldn't reccomend it if you wanted to tow every other weekend.
if given the limited option though I'd go the BA wagon, leaf springs will take the tow ball weight nicely and the slightly newer engine would be preferred. You also get the advantage of locking your shit in the boot and rear seats