Hello LazyLazuli. I can give some of my recommendations from experience combining how harbour areas work during exercise and some of the way camps are set up from where I've worked. This isn't necessarily how they should work or how every camp works, but this is what may look good for your game map.

Walls
- HESCO or other kind of high HP walls for the perimeter of your base, layer it up with barbed wire fences on the outside as an added obstacle
- If you want the most overkill wall setup, have HESCO layered with blast walls on the outside and barbed wire fencing on the outside of the blast walls similar to Camp Bastion.
- For lower security perimeters i.e. Geothermal Generator, use a metal fence with a fence gate and sandbags on the outside
- Knife rest obstacles are placed either near gates as added obstacles to block large crowds/vehicles from rushing. Usually placed 2 tiles horizontally, near gates.
- Bunkers or embrasures should be placed near entrances with visible view of who is entering the door
- Sandbags on the outside of the bunkers/embrasure walls for added protection and barbed wire fencing if you want more protection after the sandbag wall layers are added
- Have a guard room with a bedroom and small dining room near the gates for the guards
- Have a maximum of 3 entrances to your base, in an upside-down triangle shape, 6 O'Clock position, 10 O'Clock position and 2 O'Clock position including the defensive positions overlooking them
- Tank/Czech hedgehogs aren't necessary. Some of the items are optional and are more overkill than practical since you may never have to face something that crazy till end game.

Note: If you're gonna have guards using the bunkers, especially with mounted weapons, make sure they keep their distance from each other so there's less chance of them being all wiped from machine gun fire or explosions

During an attack, have your defensive positions manned by at least 2 pawns until the attack is over. Always have pawns awake at day and night cycling through the shifts to have someone available anytime there is an attack.

Health and Safety
- Have some distances between buildings in case of mortar attacks or fire in general, especially some distances from buildings away from the perimeter walls
- Have a special storage for chemfuel or other flammable/explosive resources that are further from where your colonists live for health and safety purposes
- Have fire poppers near the exit of every building
- Have more than one exit if the building/room is big enough to warrant it

Rec rooms
- Don't design the rec rooms to look military, people usually don't wanna think of work when it's time to wind down. Have normal lighting, normal furniture and flooring.
- Flood lights are usually used as a temporary way to have lighting, so outside more than used indoors and in rooms unless you really want your base to look like a freshly built FOB.

Briefing rooms
- Where mission boards are, bunch of chairs, maybe in a board room style with a table surrounded by chairs. This room is for work, try to minimize the extra stuff inside unless its more office setting stuff or some kind of store room for gear

Storage of weapons
- Have an armoury or clothes store that will have all the combat related gear in there, separate from the rest of the stockpiled items, similar to how they work irl cause those expensive objects have to be signed out so nobody nicks them to sell it on ebay.

So far my recommendations, lemme know what you think and maybe even start doing them and/or send pictures. This is obviously assuming your base can afford all the material, sometimes it's best to be efficient and work with what you have than go for aesthetic. Obviously this is the ideal way to have things set up.

You can have extra stuff inside like farms, just make sure it follows the rules of being away from walls or buildings, having some space in case of a mortar attack or fire breaking out. These establishments are high on health and safety standards, so the thought of having these small details added in make it feel more authentic

Hey Chicken Plucker, I wanna thank you for all your tip bits about how a military base is lay out. A lot of the information has has been helpful in designing my base to actually feel like proper military.

https://imgur.com/gallery/2oxWg1F

I will admit, however, I'm more used to a marriott line of bunkers across the perimeter. I'll probably rectify that later as it would probably give me too many defensive posts to hold. Also going to move some rooms around as I got lots of space to work with. Many thanks for the ideas!