We had expected family rentals but it has turned out to be adults. I tried to indicate in the listing an occupancy of four, with a max of 6. I'll let adult group renters know of your comment.
Mattresses. We have slept on them when my Son, wife and babies visited and recognize they are not the best. Frankly, I am not crazy about the queen either. Likely we will replace them next year.
Where about did he loose it? I can ask around. Usually people are helpful, unless its in the lake. If it was on a hiking trail, then he should contact the park rangers and let them know, someone may turn it in.
Boating. Weren't you going to rent a pontoon boat for a day? Kayaks/canoes and jet ski's can be rented as well at various places. If you did rent a boat/jet ski for a week you could also rent my slip as is in my listing, but with kayaks or canoes you would put them in at our dock and pull them on to the shore at night. Or, With John's truck you could haul them to the many streams and lakes in the Adirondacks for day trip adventures.
Maybe you need two weeks next year!
Let me know if you need help with anything.