I would seriously consider a modular shell with a removable top, though. It'll have to be custom, if I were to pursue something like that. But more I think about it, more I think it would be a hassle and get very expensive.
Yes, and that's the rub, isn't it? Anything good is going to be expensive. And anything not expensive is not going to be good.
I've often wished that manufacturers would make panel trucks again. Not vans, but panel trucks. Panel trucks have low load decks (like a van) but they don't sit as high as a van because the engine and front wheels are in front of the cab, not underneath it. A panel truck with a low load deck, removable seats, panel doors, and a truck-based 4wd system would be the perfect vehicle for me (and for many of us, I would think.) Because of the low load deck and high roof, you could roll a motorcycle or ATV into the back of a panel truck.
This old Chevy was the last generation of panel trucks made in the US. Circa 1967 - 70. 2wd of course although occasionally you do see a 4wd version. This one sat in my old neighborhood (Englewood, CO) for many years, though it's gone now:
I understand why manufacturers dropped panel trucks in favor of vans - for
commercial users, vans offer the same utility as a panel truck but in a shorter (and probably less expensive) package. They did that by pushing the engine and front wheels back into the cab and pushing the driver's seat up, making a 4wd conversion more difficult and expensive.
I keep wondering if Nissan will offer a version of the NV1500 or 2500 van with the 4wd system from the Titan. If they did, it would be tempting, but realistically, the potential market is probably too small.