I think it would be cool to have a small grid for structures in one of the corners of the screen that shows the damage status of each structure, by making them change to all red when they are critically damaged, and blink when they are attacked.
Basically it would show a grid filled with icons of the different structures that are currently in existence in the game. This would allow players to know if their base needs defending and repairs.
If that's too much, then have it only appear when a player has a helmet and a ckit.