As a first step, I would suggest trying to use an existing service to sell the tickets. The lowest-tech solution that will work for you is probably the best. Making bookings is a really common problem -- do you have special needs that would require you to have a highly-customized booking system?

On an unrelated note: an interesting niche on Airbnb are people who charter boats. You book the boat just like a regular place, but then they include a sailing trip, food, a guided tour, etc.

That might be something for your family to consider. Just a thought, no idea if it makes sense for you at all.