Seems like you're trying to talk yourself into this 6 person in a popup scenario. Having owned 4 over the years I can tell you that sleeping 6 in one is possible, but don't ever expect it not to be uncomfortable and a royal PITA with a capital P.
We had a Coleman Avalon, that's a highwall with a 16' box, tandem axle. Most likely the largest popup ever offered. I would never have considered 6 people on even a long weekend trip in that thing as I would not have wanted to go through all the work involved.
Get lots of plastic bins.....and a truck with a cab high fiberglass cap and 8' bed, as you'll need it. You can say storage will not be an issue all you want but it will.
Why not a 3 bunk hybrid? You can probably get out the door pricing less than the FR highwall if you play the cards right.