When we were at a 2-bedroom in AKL Kidani earlier this year, the roll-in was in the bathroom attached to the 2nd bedroom.
We had a similar situation to yours, with one couple in the master bedroom, and the guest needing the roll-in shower in the 2nd bedroom. The 2nd bedroom actually locked off from the living space and had its own internal hallway with sliding doors for the bathroom & the closet, and then a doorway to the bedroom. It was the best situation all around b/c there were actually 3 bathrooms (master, 2nd bedroom, and living space), so we all could take early morning showers without having to wait on anyone else.