What are these other "devices"? If the signal is strong enough in the coach, then any device with wifi can use it. You will probably need separate logons for each, though. If the other devices don't have wifi, then they will have to be wired to something that does. It can be a computer that has wifi, or a device called a wireless bridge, which has ports for wired connections but itself is a wifi device that can logon to a wifi network.
If the park wifi signal is weak, then you need a local repeater with a good antenna. Something like the RadioLabs O-link would probably do the job, but they aren't cheap.
http://www.radiolabs.com/products/wireless/networking/wireless-router-repeater-bridge-kit.phpHere is an article by someone who did just what you want. His solution is not exactly off-the-shelf, though.
http://www.nyetech.com/services/rv-wireless-repeater.htmThe SuperUSB Wifi plugs into a USB port. I don't know of any repeaters that accept a USB-type external antenna, but there may be one. The difficulty is that a device like the SuperUSB requires a USB device driver, and the repeaters/routers are not Windows devices and do not host Windows device drivers.