In my previous A18 world I played for 48 days on warrior difficulty, 12 (or 16? can't remember) zombies alive and the rest on standard, except for 125% XP. Didn't check my gamestage, but I was getting close to ten or so demolishers, lots of glowing zeds and ferals, spitting vultures, etc.
My horde base was very simple: five 3x3 reinforced concrete pillars with a roofed platform on them. Central pillar contained a ladder up, protected by a vault door. Platform floor mainly consisted of metal bars to shoot through, the pillars were lined with wood spikes and there were blade traps in between them. Also had a two machine gun turrets on pillars outside the base, looking inward, but they only had 200 rounds each because I was lazy.
During the last blood moon I had AGI maxed out and was using a pistol and magnum, with some quick SMG bursts in between. A few blocks got taken out, a blade trap got destroyed by a demolisher and I got hit by the vultures a few times, but other than that it was a breeze. Brass was looking tight though, so my next week was going to consist of farming radiators from houses, but then I got bored of the stagnant progression and started a new world.
I might actually up the zombie block damage a little, or maybe I should try a base that's not on stilts (or just a massive cube with bars on the sides). Felt like I was never at risk of having the base collapse.