Well, the whole RF through metal thing is usually a problem. An idea would be a few base stations connected by Cat 5e or Cat 6 spread over the park, then signal repeaters through windows into trailers that have poor signals. Interference will be a pain though. Neon or florescent lights, poorly shielded microwaves, electric motors, and any number of other things could drop entire sections off the network.
Your base stations should be outdoor routers with an array of directional antennas to increase signal strength.
You're going to want powered relays for very long Ethernet cable lengths.
I'm not going to sugarcoat it, but this is going to be a nightmare. However, there are solutions out there. You should do a search for people that specialize in area mesh networks. Alternatively you could piece together a solution with some hardware, antennas, and weatherproof boxes. You can find a bit of the consumer grade hardware in this article:
https://www.pcmag.com/roundup/350795/the-best-wi-fi-mesh-network-systems
You should be able to find commercial hardware also, which is probably more like what you'd want. It all depends on how professional you want it to turn out.
Also, use the latest standards. What you are proposing is a security nightmare as well. You'll need to take steps to keep everyone in the park from being hacked.
Best of luck to you. I hope I've given you some things to both help and think about.