The foundation of wars should be based on deception. Without it, you lose your adavtage. I sincerely doubt that this principle of conflict will change, and unless the colonists IQ suddenly drops by some 50 points, they will see the advantage of camoflage, or hiding their GP's. They have launched a spaceship, and thrive on a alien planet, I'm sure they can come up with the technology to make their guns come up from the ground much in the same way as unloading a cargotruck.. or a simple camoflage net would do the trick to some extent aswell..
Arguing that it is alot of of work involved in disguising your strong position is just stupid, because it has been proven a countless times that it usually is worth the effort. Here in Norway, we have several coastal fortresses/gun positions dating from WW1/2, and none of them are marked with a huge red sign with an arrow pointing to: Costal defense positions. They are, in fact dug into the cliff sides, or walled up, so they look as much as possible a part of the surrounding terrain. (If you want to read more about diguising your intentions in war, read up on the battle of "El Alamein" from WW2, its a brilliant example of how to trick your enemy Id say)
To solve the thing with lights,hide the GP's: Why not let them disappear into the ground if you disable them ? Turn them on again, and they pop up from the ground..
I have no information about whether camoflage will be a part of OP3, I'm just working a nightshift and had little/nothing to do, and found this topic interesting