Depends on the drive. If not crossing the Canadian Rockies, and mostly flat-land, I wouldn't worry about power. Even the slant six w/ tranny was used in Dodge trucks and a coworker used to pull a 2-horse trailer with one, even over a 4000 ft pass. I think a bigger thing is that the car weigh more than the load to avoid fish-tailing. I have a 1978 Hi-Lo camping trailer which weighs ~2800 lb. Its main feature was that it lowers for towing and was advertised "tow w/ a 6 cylinder car". I tow it with our V-6 minivan, which weighs ~4000 lb. Going over the Sierras (7000 ft pass), I could get up I-80 at 70 mph, but why risk the transmission? I usually set to "L" (2nd gear?) and go 45 mph in the truck lane up the steepest grades. Everyone on the Chrysler minivan forums say "don't tow, will ruin transmission", but can't explain how towing on flat-land is any different than driving uphill w/ no load? The engine and transmission only know the load, not whether you are towing. If a hot day, don't run the AC, even consider running the heater w/ the windows open.
Downhill is scarier, with the trailer trying to push you down the hill. Approach hills carefully so you won't have to brake in the turn and risk jack-knifing. My trailer has electric brakes, which helps. I would consider buying a 4'x8' folding flat-bed trailer, like from Northern Tools. They are cheap and light. Sell it when you arrive for probably less cost than a U-haul rental. The U-haul enclosed trailers look heavy and not terribly spacious. You can make small walls from 2"x4", then rope nets to secure the load, which will save weight. If you run short, strap a canvas luggage bag to your car's roof. I did similar moving from CA to GA, but bought an 18' car hauler trailer (perhaps too big), which we towed with our 1965 C-body. Everything was great until rear-ended at night in AZ by an uninsured driver. The highway patrolman had an attitude (didn't like CA tag?). He didn't cite the other driver and suggested it was our fault for not driving fast enough on "his highway". Not one of Sheriff Joe's guys, but similar attitude.
Re attaching the trailer hitch, you might do like I did on my C-body. I bought a "universal hitch" at K-mart (?). The width was adjustable. I attached the sides to the rear frame rails. They are thin and slid up between the frame inner side and the gas tank. It came w/ wedged shims, which helped because the frame rails aren't exactly parallel. It also came w/ a wire to fish the bolts thru the hollow frame. An A-body is very similar, so "should work". Only downside is it has a 1.25" square receiver, rather than the more standard 2" sq, but rated 3500 lb (Class II, I recall), which still matched the trailer weight.
