Mark,
I'm sure once the paint cures it could probably be color sanded and buffed. However, I think it looks great as it it. Like you said, it's a working wagon. My car had been a daily driver and working wagon for many years until I took it off the road. It's seen a few NY winters before finding it's way down here in Flora-duh.
I recall back in the late 60's, early 70's, I used to help my dad do house painting, mostly interior work. I painted a customers kitchen cabinets with Interlux paint. They came out very nice and lasted for many years. I impressed myself. 😛
I like your battery tender idea. I guess the car cover renders the solar panel useless?