I can tell you that my kids wont outgrow the bunks, they are 4' x 6'. We did our shakedown trip over the weekend, and it was a bit tight for the 5 of us, and my trailer is 28'. Kids get restless, and need something to occupy themselves with. I have seen quad bunk trailers that had an area between them in the rear that would make for a gaming area, where they can sit around and play board or card games, but that too will get old. Maybe setup a tv on the back wall for them.
So the big question, do you sacrifice your sanity for them, or for you? Either way you will lose your sanity being couped up in a small trailer with 4 kids for any length of time. I found out right away that lack of counter space for cooking meals, or just washing dishes can be a burden. I am going to get a pair of those folding shelf brackets and add a countertop to the end of the cabinet by the sink in mine, every bit of space helps.
I just checked that floorplan and it is what I would get if I were in your position. The kids would have their own area, and so would you. I think I had actually considered that trailer, but was too big and heavy for my TV.
