[VTbiker]

I started with a passenger van for the safety. Took out the second row seat and left the third row double seat. Built an East-West bed between the windows. A double size blowup camping mattress works for the kids on the floor between the front buckets and bench seat.
A new option for 2020 is the crew van, but that seat is right behind the first row, so you would have to have a kids bed behind that.

 

[Kabouter]

I like the systems that mount car seat specific tie downs. I have seen them where the mounting brackets are recessed into the floor, so you can cap them when you are not driving and have a lot of open space. Then, once your kids get older and can use the lap belt, you can add bench seat.

 

[glentlo]

We upgraded our existing 2011 RV seat to convert it into a double bed with the RecPro charles collection double recliner 58. Very pleased with this recliner, soft comfortable, easy to sleep in. Almost reclined to a flat position when hugging the wall.