I travel with 4 and have 2 seniors that no longer can walk/wear a collar or harness due to disabilities. When walking on a leash was no longer an option I brought along my ex-pens with when RV'ing for them.
They are set up along side the MH under the awning and I put a precut sunscreen material under the expen. They use this to go to the bathroom which is picked up immediately and then they stretch out and enjoy the day safe in their ex-pen with fresh water and a bed. I have metal pooper scooper to pick up and a long wood handle with a rectangle wood brush on the other end for scrubbing down the sunscreen to keep it clean.
Throw a nice comfy bed in an ex-pen and both your seniors would be able to be with you outside all day and night! You have very lucky dogs that have an owner that takes the time to cater do their needs so they can still go camping with the family. :C