. .... There isn't anything in my home that is on during the day that isn't at night. I suspect it may be something with a neighbor or neighborhood. You can't filter that...
Actually ... you can. You can install a line filter at your service panel (AKA fuse box). This could filter out rouge FM or other signals carried into your home from the power lines.
You may have a phase problem that degrades the line signal in your home. A brief explanation: Your 220/240 service at your service panel consists of two separate 110/120 power lines (each line is a separate "phase" of the service) that enter your home. Typically one side of the panel (AKA breaker box) is feed by one line and the other side by the other line. This separation of the two phases can cause commutation problems for X10.
An uninterpretable power supply (battery back-up) can absorb your X10 line signal. Also, those little battery charging devices can play havoc with a X10 line signal, even sometimes when NOT ON... just plugged in. Cell phone chargers are infamous for creating line noise... even when the phone isn't plugged in.
These issues can be addressed aggressively... or passively. The decision is personal, and there is lots of information here on the forum about such issues.
Your system is small enough, it should be possible to relocate camera power sources, and your transceiver to the same phase. Often it can be as simple as mapping your circuts and selecting which plugs to use. Or just flipping a few breakers off, and see what goes OFF.
I might try the extension cord idea just to see what happens...although most of my plugs have power strips in them...I'll keep you posted if things improve....
That is what I would do.