We've had 6 in my buddies 16x20 many times. Cooking has to happen elsewhere though. 7 with personal gear and a stove is doable as a sleep house but not much more. 3 of us spent 7 nights in it on a Montana hunt and it felt like a mansion.
I finally picked up one for my wife and I this year on a deal I couldn't pass up. Mid-90s era Davis with stove. Inside measures just shy of 14 x 15. Great size for 2 with cook table. 3 would definitely fit too.
Cant go wrong with Davis. Also I did the same thing as you and special ordered from them, had another door added and screens to use during the summer for family camping. With a investment this big just make sure you get what you want even if this means saving a little longer for it
We lived for years in a 10x15 with 5 ft side walls. It serviced four adults nicely and was small enough to pack. Years later we added a 10x12 cook tent with 3 ft walls because it was available. We connected them with a tarp causeway. The early years our kitchen was in the causeway. Instead of cots we packed a bale of straw and put a tarp over it. It was comfortable and warm. We always built a rock base for the stove.
It worked well for from the 70s through the early 2000s when we started hunting from the ranch to be more flexible. For hunting we built 4 camps over that time. For work a differant camp every year or more as we moved from site to site. You don't need much room for kids. I raised mine in a dome tent during the summers and that included two kids and a dog ( early warming system).