I love the idea of building an MCR (Mobile Construction Robot) that you drive/glide to the area you like.
I would also love to see a RTS view introduced with PBS. Drive the MCR to the area you wish to claim and deploy. This switches you to an RTS view and allow you to see what the terrain around the area is like for "Smoothness" Green tiles = Available, Red Tiles = Blocked.
The MCR should then deploy and open once you confirm the location, the driver of the MCR will be back in a robot (Perhaps of the players choice OR a Construction robot). The MCR must then be 'Secured' or 'Constructed'.
The original concept of PBS was modular buildings connected by pipes. Pipes being easily destroyed or intercepted while the main buildings would be massively resistive.
Terraforming should allow you to make more tile "Available" by making them at the same height as the deployed MCR and a near flat slope. Placing a building could cause the terrain to flatten underneath it as long as all times are at the same height and whatever an acceptable slope is.
TL;DR - Perpetuum does not suit static buildings are long periods of time. I would like to see a base where the main cost is placed on a control centre and modular buildings can be pipelined together for a low cost. This means that a base can be abandoned or left when minerals dry up or taken over by the enemy destroying the control centre and placing their own there.