In case of the lamps it could graphically simply be the same model on top of a piece of wall, and the way you (as a player) would do it could simply be placing the lamp on a piece of wall:
And in case of a turret it would be basically the same, but requirering a larger "pedistal":
ImageDepending on how complicated you wanna make it, you could make the height difference require a long handed inserter to reach, if you want to auto reload a bullet turret.
Anyways, it was mostly a thing that I thought would look cool on my little "fortress"
I'd love some feedback, so tell me what you think (And I'm talking to the community in general here ^^)