Tim and Becky are good folks. I photographed their wedding ( in Stanley) years ago. And...my first date with my future wife was breakfast at the hotel. It was the previous owners but the building was part of it and we are still married.
Tim did a late season MF a couple of years ago. Haven't seen the separate building out back but that sounds like you could pull right up and it might be perfect. I need to take a look at that next time I am up.
Down at Sunbeam they might be renting out some cabins this year. I know they have done some wedding receptions and parties. Need to check with Doug at White Otter. He runs a daytrip company out of there and does river food, rents gear and such. Much more primitive but tons of room for gear, trailers, places to hang stuff to dry etc. Not sure if they will do it but I'll try to find out.
Lots of folks use the big main hotel. Mtn Village. The only benefit I can see to that is that they have a private, reservable hot springs. Covered with barn doors to open up to the views. It is an awesome hot tub. Other than that, not so much.
Some other friends own these cabins.
Danners Log Cabins Stanley Idaho
Not sure how close or handy trailer parking would be but they are cozy, clean cabins.
Bridge Street is good food ( didn't know they did cabins). As is the Sawtooth Hotel and it's sister restaurant The Sawtooth Bakery ( don't be in a hurry there is often a line)
Lots of other places too. Here is the chamber website:
Stanley Idaho Lodging including Stanley Hotels and Motels