Taking Cats Outside of RV

We travel with three cats. Our older two cats that are no longer with us were used to going out on leashes or in our pop up screen house. The third and largest cat was too much to handle bringing her out so I did not and she got used to not going out. She would lay by the door and watch the world. I now have two young cats and the big cat. I have taught the young cats to stay away from the door when we are going in and out. I do not take any of them out as it is a learned thing for them, and what they don't know they will not miss. I am getting older and harder for me to shuffle the cats in and out of the motor home. If you are interested in having the cats outside with you, maybe try one of those large canvas/screen pop up dog crates? This is where our cats stay while we are on the road, the ones I have are about 3 ft by 2 ft. You could pop it open in seconds, put it outside and set the cats up for a sunny afternoon. They store flat in one of the storage bays or under the bed.