Look at Cruiser RV. I have both a full size queen bed and a tub for the kids. We also have a quad bunk in ours. Our empty weight when I weighed it coming home from the dealer with propane and 2 batteries was just over 6000 lbs. we have been adjusting what we bring with us and we have carried between 6600 - 6950 for our trips.
I agree that you will not get enough hot water to fill the tub we get enough to be able to give the little one (he just turned 1) a bath and he has fun and it is warm enough for him. The rest of the family gets a quick shower.
