The 777 camera is powered with a 12V wall-wart so I would not expect a problem using an inverter; I have run mine briefly on my Xantrex Freedom25 inverter/charger. If you had any issues you could easily substitute a different power supply.
Depending how far your porch is from the boat; be aware these are not stunningly high-resolution cameras. The "3X zoom" feature give a pretty blocky view. The quality is ok for the length of the boat, but I did use two, one on the foredeck and another at the cabin entry (I wanted more detail of the winter cover over the cockpit area). Bright light does cause some flare. You'll be able to see that the boat is still afloat, certainly. ;-)
I just picked up a "dummy" security camera with dome (the camera is dummy, the dome is real) to see where I might mount it outside more permanently; possibly hanging it under the (future) radar scanner.
1998 Jeanneau SO45.2