Don’t know about the metal gate/walls cause is that even build able in game, would require welders forges and lots of metal, not sure how high-tech you want the evac shelter people to be. I’d see them as more of a typical apocalypse type fort, use of the raw natural materials near by to build it up, as venturing into the cities to get the advanced stuff is dangerous.
For defenses the wooden palisade gate makes sense, with wooden walls, pits with stakes in them to keep monsters away from the walls. Nailboard traps placed around.
The solar array, again how high-tech are they? A few solar panels they were able to get from cars out of town, or a little bio diesel generator, or a few pedal power generators.
By the well add a standing water tank.
Make a big pit a bit outside the walls, similar to the fema camp ones, they use for burning any of the infected they come across.
Could have a small livestock area.
Have a basic butcher rack the hunters use for the game they bring back, makeshift beds, as the sheets and rags for real beds might be harder to come by.
I’ll try to think of more stuff got to walk the dogs.