I will also say - before they are finnished - that some turrets may need floating or armor modes or both.
Missle silos (Hacksaw, Defender) could shoot flail like missles and it would be fine if 90° turning into the sky would be possible.
3 legs which can retract (lower the turret) and stretch (move the turret vertically) could look very good.
To combine both, I have a suggestion, but I don't know if the UV-map or normal map would be too difficult for it...
... let's start:
2 parralell legs are like human legs and have the feets at the front, the knees at the back and the upper end directly above the feets. The third leg is in a reverse direction and connects the bottom and turret at the back.
This legs are able to retract to only the heigh of their diameter. - the turret can get deeper down by a 180° flip (like the current floating razzor) or lowering the platform where the feets are on.
It can have a hut to protect itself in an armoured mode.
The the 2 paralell legs should hold the main weight - the upper part can be a bit shorter if the turret needs to be moved backwards to fit into the hole.
The third leg could have a longer upper part to compensate the shorter part at the other both legs - the feet needs to move an equal distance toward the center of the platform.
Lowering the angle of the back-leg and raising the angle of the paralell ones can turn the barrel and let it point upwards. I think you are able to imagine how to move the barrel to let it point downwards ;)
Turning the platform which the legs are on can turn the barrel around the Y-axis.
The advantage of thoose legs are, that they can even have 2 or 3 knees pointing in alternating direction to get more lenght with an equal platform diameter - or you can alter the platform altitude.
