I'm just going to put out whatever ideas come across my mind here. Here's what I thought of in my first play test:
Your original starting base, is larger, stronger, and can recieve upgrades to have automatic energy generation for when you're away
The current bases in the game, you can establish them anywhere. If you can link them via a power cable to your main base their power can be accessed at the main base
Cables that can be placed and routed around by selecting to start placing a cable at a building and driving to what you want to link it to.
If linked to a power source (a main base or outpost), it will detect any enemy tanks in an upgradeable radius and make a notification on the map
A fence that can be placed in lines. Can be used to section off areas, and if connected to a power source, will make a notification similar to alarm Tower if attacked. A gate can be built on an existing fence, and will only open for the builder.
A road placed in the same way as the fence. It provides bonus movement speed when driven on.
Maybe to build the things like roads, walls, cables, etc. you need a different vehicle you get at the hanger, something like a construction vehicle?
These are just random "that'd be pretty neat" ideas, so they're probably not that good, but I think they'd be pretty cool