I think the front bunk/couch arrangement the couch being anchored to both the floor and the wood rail fiberglassed to the wall make it a structural element. It doesn't support the roof but it does help keep the front rigid and braced at the corners.
Which floor plan is it? That would allow people to more easily visualize what you are describing. I think you are describing layout #2 from here.
What about a low cot running from the potti closet back toward the dinette bed? Like one of these. https://www.amazon.com/MARCHWAY-Ultr...=fsclp_pl_dp_7
Or even a taller one.
Moving the porta-pottie out to one of those small changing bathroom sized tents might be an option if one is using the pottie closet for sleeping.
I'm thinking don't need to sleep inside unless the weather is bad or just stopping for the night to sleep while traveling and don't want to set up tent.
I tend to agree it is an odd modification, one that would appeal to only a small market segment. Unlike say a front couch into a front dinette and bed. That has broader appeal.
I would also say that on trips you want the pottie you would probably "lose" your second bunk. Might be better to focus on a solution that will work well with or without potty in the room.
The alternating of heads and feet at opposite ends does seem to give more room. Would provide a less intimate arrangement. I think I'll still use the front couch as second bed when brother in law and myself go camping! My rule is only one hairy back in the bed is not generally negotiable.
Still if most times you can use a tent and you are both comfortable the opposite ends and tapered sleeping bags could work ok for the few times setting up the tent is not workable. While allowing the potty closet to always be available. The real fight always becomes who gets the outside of the bed.
Of course a lot of older couples would like your arrangement of storage and toilet. Selling your camper might allow you to purchase a different floor plan better suited to your needs. The only problem with the porta-pottie under the couch is the thing is pretty low. If I could squat like that and stand up again I would still be using a tree as a backrest.