I'd try to make a provision for shore power charging on the road. Redundancy is a good thing. My integrated Prosine inverter/charger will start charging at around 100a. It uses a temp sensor on the battery bank to help max out the charging rate. Useful for quickly feeding a kw-hr into a bank w/o waiting around too long.
Many of us portapotty partisans store it under a shelf and bring it out to an aisle for use. I think my size 14 feet take more floor space than the potty itself.
Not an unreasonable idea to have a dedicated-toilet spot planned for. If you found the potty or equally good lined-bucket not to your preferences you could give up some nonessential space like a storage area. I'd still start with the noninstalled since its cheap and easy to care for.