this mod is great, however it is not practical to use in death worlds as the bunkers basically die so easily from big inital attacks and it is not worth obtaining in the first 2 minutes before initial contact with the enemy due to the copper requirement and low health. Granted the copper requirement is doable, because its health is so low it isn't worth rushing over wooden walls for defence and by the time basic turrets are setup with walls this is never needed.
suggest making the bunker feel much more tankier with a 3-4x in health on both variants so it can be a nice safe haven, modify wooden version to only cost wood but maybe more wood for balance so it is rather costly on wood and not worth making a wall of them. (i.e 50-60 wood?)
if any of this maybe contradicts design decisions, making all the health and costs modifable via startup param's would allow someone to tweak to the specific gameplay feel without effecting others.