I agree that a Landy isn't the most comfortable of places to spend a long period of time. I am 6'2" and I can never get the seat far enough back to get enough leg room. Then there is "Land Rover elbow" just thinking about the lack of room for your right arm makes my elbow ache

I wouldn't fancy spend three nights in truck cab Landy. I am surprised you can still walk!

Something van based is going to ideal for what you need. Or maybe larger you could go up to a light commercial based on a 7.5 ton platform. That'd give you plenty of room then.