RVing with 3 children under 5

I would put the baby in the passengers front seat facing the rear and in a properly sized baby seat. Then the non driver parent would sit with the two children on the seat belted sofa just to the rear of the driver so the baby could be seen and attended by the non driving parent. I would not remove seat belts from children or baby seat while traveling so stops for bathroom and feeding would have to be made as needed. Many RV's have that set up. Booster seats may be needed as they restrict the children from slipping out of the large adult seat belts. I had three children in less than two years and had all three in child seats with seat belts across the back seat of our 1965 Dodge Dart convertible. They were all forward facing and I had to use car seat belts and child seat straps, and a toy attached to all the front loop bars that were padded. Of course they all wore hats and had sun tan lotion, and their Mom paid attention to them as I drove. We usually had songs to sing to make the ride a fun thing for them. Enjoy them as they grow up fast when they are close in age. I think you will find the auto rules differ from RV rules for front seat. That's because there is no back seat that faces forward in most RV's as they usually face sideways. Plus most RV's do not have front seat airbags which is why child seats can't be in front of cars and vehicles that have front air bags, as they injure the baby when they deploy.