If you are willing to go to just under 30 foot length (just slightly more than those 24-26 numbered models that are actually 27-28 feet long) look at the two-slide floorplans from Forest River and Winnebago/Itasca, 2003-2008 or so. For these, sofa was in front slide, opposite a patio-side dinette, and queen in back slide. Winnebago put two seatbelts in dinette, two on sofa. Mine has seatbelts installed in all seven seating positions in the house, was not hard to do.
W/I model number was 29B; I know F-R had an equivalent because someone in our RV club bought one and used it for about six months before trading for the similar Winnebago.
