If you have a scanner that includes CB in it's service search section, you could ascertain any active frequencies that way, it's better then turning that channel control knob endlessly the way I had to do, many moons ago. If you don't get any replies here in a reasonable length of time, PM a moderator & request that your thread be transferred to the CB radio forum. How is your other thing coming along?
There is a neighborhood watch group somewhere in J-Town that uses channel 4, check it out & ask for Ironman, he runs the outfit. Also monitor channel 19 for truckers on I-95 giving radio checks & smokey reports & channel 9 used to be heavily monitored by various PDs for emergency help request from motorist years ago, however I have no idea if any PDs actually even monitor it anymore. Have fun.