1 gigabit of Internet is around $500/month here for a business class connection, with the caveat you can't resell the bandwidth (so you'd have to have advertise it as "free" wifi)
Properly managed by a decent router and firewall a connection of that speed could easily support hundreds of campers and even allow basic non-HD streaming (Netflix low-q needs less than 1mbit)
Problem I see, that price is under a multi-year contract - what happens when winter gets here and the park is closed for the next 4-5 months? Similar situation for the southernly afflicted, 2-3 months of super hot weather scare off all the business.