Hi James, Probably nothing wrong with the Icom radios, but for your purposes I would perhaps go with a used Motorola GR300 or similar repeater, or even a couple of Maxtrac style radios with a simple delay cable for tx keying and audio.
Program the radios with all of the event frequencies which you are likely to use, and simply switch channels as needed when you get each frequency assignment. These types of units are generally inexpensive, available, easy to program or get programmed, portable, and reliable. As to the duplexer, that could be a tough one if you are often changing frequencies, especially if the involved frequencies are not close together. You could perhaps use two antennas if the seperation between transmit and receive frequencies is great enough. Successful portable VHF repeaters have certainly been done, just a matter of tailoring the system to your needs. Good luck! - Darrell/KA7BTV
