My parents travelled for months at a time in a van, albeit with window van with a high top! It takes patience and co-operation for two to manage in a van more than anything else.
The two front seats had swivel bases and they had a pedestal table that went in between them. Dad had to be seated in the drivers seat before the table got put in place.
The bed was set up so that they slept heads against the back door so that, while they had to get out of bed at the foot, no one had to crawl over the other to get out of bed. That gets way old way fast!!
The porta pottie was in a low cabinet on the passenger side and the kitchen was maybe 4' long at the drivers side.
Storage was 2 big drawers under the bed, both sides of the bed base lifted up over the wheel wells to store odds and ends that were seldom used. Additional storage was accessed from the rear doors for sutff like the propane stove and barbecue. They also had RV style small cabinets around the perimeter of the van in the high top as well as the space over the cab. It held all the cooking appliances and some food. They used a cooler with ice but this was before the 12V compressor coolers were available. It got moved around a lot...
The most important thing in making it work is the co-operation and the realization that you both had to travel light. Dad would get out of bed first, dress and go for a walk while mom got up because you can't pass each other in the hall...
They went from Ontario to BC and then south through the western states doing a big loop like you have planned and then another time they went to Alaska and north through to the end of the road. Also did major trips down east. Wonder where I get itchy feet from....
It can be done but I personally wouldn't want to try it without the high top. It provided not only standing room but also all the extra storage capacity that you wouldn't have without it.
