Ok so this new feature could bring a lot of realism into the JUNO RP or Sandbox gameplay, there should be a way to save a location in any celestial body as a "Base" without it being considered as a Launch Location or a default "Save & Exit" base/lander Craft just like we have from the community.

The Base itself would need transported resources to be built, like materials, so a new part needs to be added to the sandbox and carrer modes, named as 'Material Cargo' (it would look just like a fuel tank, except it could contain the following materials: copper, aluminium and aluminium alloy as its "Fuels").

After reaching the lunar surface or any body's surface, you need to walk outside with the Drood and select a button on its informations UI called "Create a Base", then click "Yes", after that a Waypoint would be created in the cubemap and it will just look like the Target Selection feature, except it will be Colored (just like a minecraft waypoint, in which you can select its color and rename it if needed)

Waypoint Demonstration (It could be colored only in the cubemap to be easily spotted)

Ok but how can I build the bases?

With the resources onboard of your lander, you need to be at least in a range of 200m from the center of the base site/landing site, so you can open the Material Cargo selection UI and click the button "Create a Base Structure" and after that you select one of the following options to create your base structure/living base.

The Bases will be preset ones, on which you could select from 3 or 4 different options of bases of your preference:

Here are some Ideas of the preset Bases.

Dome Base

Cost of Building: 30 Tons of Aluminium, 10 Tons of Alminium alloy and 5 Tons of Copper (Just an Example since I'm not an expert).

Scientific Outpost/Base

Cost of building: 15 Tons of Aluminium, 5 Tons of Aluminium Alloy and 2.5 Tons of Copper.

Greenhouse Base

Cost of building: 10 Tons of Aluminium, 10 Tons of Aluminium Alloy and 7.5 Tons of Copper.

PS: The greenhouse base could be used in a future for living support systems and career contracts to be more realistic.

FAQ:

-Q: How would I place the Base structure on the surface?
A: There will be a rotation and translation marker just like shown in this picture for the available places for the base to be built:

If the structure can't be placed, the structure will be entirely painted with red (and if you press the button on the UI to place it, i would say "Error, You can't build your base here"), if the structure can be placed, the structure will look painted with green and a message will appear after you press "Yes" in the UI: "Congratulations, you've built your base".

-Q: I didn't understand what you meant with "Base" and Base Structure.
A: Ok so they will be two separate things, the Base will just likely be the Landing Site, while the Base Structure will be the Living Base. As I said before, you will be able to create the Base (landing site) if you step outside of your lander in the body's surface with a droo and click on his selection UI to "Create a Base".

PS: Also, The "Bases structures" after placed in the surface will be solidified, just like the other buildings in the DSC (Droo Space Center) or the Other Launch Sites, except that you will be able to select its own Menu that features a "Crew Capacity" thing, to place the astronauts inside and walk out with them at anytime.