My advice would be to divide your wish list into wants and needs. If your weight limitation is real, then I would go with a basic 12' box without a slideout. I would also skip the interior shower and toilet for more room also. A rig like that can sleep 6 easily and up to 8 if you have smaller kids. It will also top out around 2800-2900 to be able to tow it. It is exactly what we have and we have slept 9 in our and just back from a 19 day trip with 6 of us and two dogs, all good sized people. If you need a porta pottie, you can bring one along, but a 12' box will give you everything else you need. As noted above, you can find them used for maybe $3-5K if you are willing to look and travel to get one.