I believe you can plug in the antennae cable to the "Cable Input Jack" on your rig, and you should get reception on all 3 tv's. Not sure if the built-in signal booster (green button) should be on or off. I suppose it depends on whether or not the antennae has a built-in booster. Also, not sure if your tv should be set for "Over-the-Air" or "Cable" signal. My guess is OTA, but I'm sure someone else will chime in with the correct answers.
Good luck and Happy Camping!