Mate, that looks great. I've designed my own "teardrop/tvan" but your method could be an easier option. I'll be very interested to know the final weight and costs if that's okay? To strip it out internally and start again makes it a very flexible solution.
The doorway access step looks like a possible clearance problem. Any ideas to raise the floor and make an external fold out step or similar? What brand and size are the access hatches? I am hunting for some of those.
Good luck and keep up the great work!