@Hasse18 Your maximum occupancy should assume that all guests are fully-grown adults, since there's not an adjustment in the system that would allow a family with 2 kids to book but not a group of 4 grown-ups.
It sounds like 3 would be the maximum number of guests that would be comfortable in this set-up - any more than 1 person sleeping in the living room, and the reviews start describing the conditions as "cramped." That living room becomes strewn with the contents of people's luggage (especially if kids are involved), and no longer works as a common area once the bed gets pulled out.