@m_pags - what an awesome spot! Thanks for hosting us. It was so much fun to get the first few rips of the year in with you. Amazingly skiable in the strong winds too!
Here is my take on amenities:
For our site we have a gazebo for shade, small locked gear/ changing shed, lockable gas storage, WiFi, and a regularly serviced porta potty. All of that works pretty well and keeps us in reasonable shape throughout the season.
We do not have a club boat, but that has more to do with our 30 year history than what actually makes logical sense. I’d definitely do a club boat if starting from scratch. Not necessary in my opinion to have a current year hull for slalom, current speed control is nice but not essential for off-season (your Malibu felt great yesterday).
Insurance is just the USA waterski + boat insurance and of course a good umbrella. We name the property owners as additional insured, but technically our water is State owned so you may need something more.
Looking forward to skiing with you up north and in sunny Florida next winter!