DKM_Fam,
We have a 2005 GBM Cruise Master. One of the things we liked about it is that it had 12 belted positions (driver, passenger, 3 on each of the two sofas, 4 at the dinette) provided from the factory. The great thing about having so many seatbelts is that it gives options as to where they want to sit. Our policy is belted while underway. If they need a bathroom stop or unbuckle for any reason, they must get permission. If I (driver) deem it's safe to do so (low traffic, straight road, creeping along due to construction/accident) then they are allowed to go. When they were little, my wife went with them.
It sounds like you're responsible, so I'm sure you can find a safe way to keep them secure.
As for the bedroom, I installed 3 non-retractable seatbelts across our bed in the back from
SeatBeltPros.com. I installed 3 because we had 4 children of varying heights, so everyone had at least one belt across them. When we travel at night, we buckle them in back there while they watch the TV. I just didn't want them rolling out should I have to jam on the brakes (although the mental image of that is amusing :) ).
They connect with an eye-bolt to the bed board and are removed when we don't need them. I think I got the longest ones available. They also sell the hardware that you need. You even have your choice of colors.
And...it's a reason to put eyehooks and straps on the bed for later adult playtime! LOL :B
Safe travels,
~Rick