@Vivian119
I think I will be a lone voice here but I do not charge for extra people. I set up a high price based on assumption that I will be at almost full capacity. If small group books- they must want to be able to spread out and are willing to pay for the luxury.
I personally find larger groups to be more easy going. If something goes wrong they do not tend to fret. Smaller groups nitpick and need a lot of hand holding.
I set a high deposit and overlook little issues. I cannot even imaging calculating the price based on teh number. Someone is coming, someone has cancelled, someone sneaked in- I do not have the attention span for that.
I do think I would not have had the occupancy I enjoy if I had a smaller capacity, mainly because competition in my area is huge and this makes me stand out.
As for beds, this is what I have for extra:
Floor mattresses- these are great because they are comfy and I can tuck them under the big bed if fewer guests are coming
Air mattresses- only one set of guests did not like them but I personally think it is not my standard and slowly replacing those
Foldable floor mattresses- these are my recent addition and the kind I found is amazing. Only $120 for queen, folds away and feedback from guests has been great.
Futons from IKEA- you can fold them to be a small couch and open to sleep. I hate these for multiple reasons but they serve the purpose.
For your third room bunk is a great idea if it is a smaller space. Otherwise I would recommend double or queen. Cheaper and more comfortable.
Good luck with everything!