Yes - if the camper doesn't work then that isn't a great option. I think the extended cab might be desireable to any travellers - great if you have dogs and would allow an in cab sleeping area perhaps for one person. Having space in the front for a small fridge and gear is especially nice when there is no pass thru on the camper. Also would allow the passenger seat to recline for napping while underway.
You might talk with Rebel off-road about the Isuzu double cabs and their upcoming retrofit of 4wd to them. Other than that I don't know much about them but I have seen them in Australia a bit when I was there.
From what I've been told, Rebel is just doing the one-off for the boss. No plans to make a kit at all. Although if you really want this done, PM me as I have further info...
Many great DoKa's here!; https://www.firetruckmall.com/AvailableTrucks/European-Style-Units