Sculling should be a perfectly adequate way to move your E29 around. I wouldn't want to try to row a boat that size though. What's the beam, about 9 feet? So you'd have 4' of oar inboard of the locks, and I'm sure you'd need 8' at least to get them into the water from your rails 3' up. Then you'd have to stand, and try to have any leverage rowing with those mammoth oars. I just can't see that working at all.
Lin and Larry Pardey have been cruising their wooden 30-footish boats around the world for decades with no motor. They use a sculling oar, and have no problems. I'd bet their boats weigh double what your E29 weighs!
However, I think you want to get/make yourself a proper sculling oar. It's not just a single rowing oar that you hang off the back of the boat. It's shaped differently.
Google sculling, or sculling oar, and you'll find lots of good info on the subject.
Sounds like a great idea to me. Have fun!
Oh, one more question. Is it really necessary to winterize your A4 in Maryland? Why not just put a lightbulb in the engine compartment? If you're in saltwater you probably wouldn't even need to do that.