In S. Ont. we have several travelling ski schools, some for adults, some for kids.
These travelling ski schools go to different ski areas on a regular basis, and have arranged in advance to teach their members on their own.
They even visit some of the private ski clubs in this area on otherwise slow mid-week days.
The resorts are quite happy to sell 50 to 750 daily lift tickets, and some lunches, and for this they don't mind forgoing the ski school revenue.
There are also a few groups with only a dozen or so members in attendance who also use their own instructors and coaches, again with full support of the local management.
Staff for the these ski schools are CSIA/CSCF/CASI members in good standing.
Some of these travelling clubs go to areas in other provinces and in other countries for weekend and longer trips.
Similar story -- many areas will welcome these travelling clubs, and are quite happy to have a busload of customers
The key to success for all of these groups is to communicate openly in advance, and to work in co-operation with resort management.
Just showing up unannounced with your group won't usually go over so well.