I didn't notice your post, on a new page, till tonight.
Your solution is terrific, except for losing the hitch, and I bet it is more stable than mine. Three points, all the weight on the hitch.
Your Sears mounting brackets are entirely different than mine, which I couldn't figure out a good way to incorporate.
Tubing benders are a lot of fun, once you get the hang of marking out bends. Just watch the conduit, at the bolt holes. It is not super strong, esp once it rusts on the inside.
I too got a 4-bank charger on advice from mfrerking, and it is worth the money (not sure wife thinks so.)
Speaking of hitchs, I pulled an aerator with Zeon last week. Better than I ever hoped. It will run all day with the mower off; plenty of power, never even felt the aerator pulling; easier to get on and off the Zeon than a tractor to actuate the aerator; and the silence was amazing! I could hear the hawks cry overhead. Best of all was the unexpected benefit of controlling a trailer with a zero turn. Backing up is so easy what with being able to waggle the hitch any direction i want. Very glad I took the risk and bought the Zeon. (Wife still sceptical . . .)