I also have five kids, so I feel for you. Mine are a bit more spread out. My youngest is 9 and my oldest is 21. If yours are all teenagers, (13 to 19) you were some busy bee's for six years.
We started with a Trillium
4500, and a travel van. Four of the kids slept in the trailer, and The adults, and the youngest, slept in the van. This setup was more about getting from Calgary to Manitoulin Island, in Ontario. So showers and bathroom facilities were not really a consideration. Besides, most camp grounds have that covered.
I am not super familiar with other brands, but I do know my Trilliums. There is an option for a fold down bunk above the dinette which would allow a 4500 to sleep six. Though three of them should be smaller. Like less then 100 lbs or so. Then if the adults sleep in a van, then that makes eight. Hey, one of your kids could bring a friend.
Other options would be a Bigfoot
with a gaucho, That has 5 beds, and a bathroom. And enough floor space for more. You would still need to sleep someone in the vehicle though.
Also a tent might help. Kids love to have their own place.