At NATCOA, we have been discussing a standard GMRS frequency for Truck Campers. We have decided on using channel 19, privacy subchannel 5. This is what we used on the caravan this summer. FRS/GMRS radios are cheap ($40-$80 depending on range) at places like Walmart, and we figured if we push a standard frequency, it will enable you to communicate with other TC's you meet on the road. If you use channel 19 as such, you can still communicate with someone on 19.5, but using a squelch channel, minimizes the possibility of interference with others using these radios.
By the way Channels 1-6 are combined GMRS/FRS channels with a high power, 7-14 are FRS only with low power & 15-22 are GMRS only with high power. There are 38 squelch (sub) channels for each main channel.
It would be nice to be able to say hi to other TC's you pass on the highway.