Unusual portable network

Hey,

I have a bit of an unusual network set up need, and would like to pick the collective intelligence of the group to make this work.

I work for a touring theater show, meaning every 2 - 3 days I am in a new theater with a different internet connection. At times, I connect to a wired ethernet connection, at other times I can only connect to the theaters wireless signal. I travel a small wired LAN setup - wireless router, network drive, printserver for a couple of printers. There are 2 - 3 other users of the system, which connect through the wireless router. Currently, when the theater has a hardwire ethernet connection, I can plug my wireless router into it, and the system works fine. However, when the theater only has a wireless signal to connect to, I have to choose between connecting to the internet or connecting to my LAN.

I need a setup that allows the other users of the system to have a seemless connection, as they are all non-technical oriented users of their computers. Ideally, no matter the internet setup, the other users would see the same SSID from my wireless router and be able to access the LAN or the internet through it.

I'm not a network guru, but I do know my way around various router configuration menus and have a basic understanding of networks. My question is, what is the easiest way to set up this portable network - can I reconfigure my router depending on the internet connection available through the local theater? Have it work as a bridge sometimes and as a router at others? Am I better off adding an WAP to the system when I only have a wi-fi signal available in the theater? What pitfalls do I need to look out for? Is this even possible?

Thanks for any advice,

Dan