I don't worry about keeping my spikes in pristine condition. In SP random gen, I rarely take over POIs but instead build small bunkers of cobblestone with subterranean forge, workstations, and campfires. I usually have a couple rows of spikes around the bunker for when I am there. Then I am out and exploring or gathering. The wandering hordes will find me and not my base. Part of the reason they are GPSing to your position is you are repairing your spikes for too long. Stay in a location long enough, they will find you. Steel spikes should last quite a while without needing replacement, so I agree with the others who have said you don't need to keep them pristine. Try an experiment; if you are the 56 day horde, repair your base as needed. If this takes a full game day, fine. Next day when the Z's stop running (or if you want, at night sneak around) and leave the base. I don't leave multiple forges or campfires running while away. One forge smelting metals and maybe making iron or steel arrow tips while I am away. Find a temporary base to set-up near a town or just explore and use a POI to ride out the night. Do not place a sleeping roll when you are out. Risky, true, but it could save some things at your base. Then time it so that you return to your base the day of the next 7 day horde and see the status of your spikes. Are they destroyed? Did they only take a little damage? Do you need to fully replace them? Part of the beauty of this open world is to try things and push yourself to avoid old habits and try new things or ways of living. My guess would be that your spikes will be fine overall, maybe in need of some small repairs. Restart your forges and campfires, since your getting a horde anyway.
In MP, my partners and I usually use a POI in a town or city to start, but we are out exploring, looting, and gathering resources once we have some defenses in place (not even wood log spikes) and only have an occasional problem with a wandering horde mucking things up.
Sleepers outside a certain radius in larger POIs are an issue, but if you are aware of it, you can prepare for it.
Good luck. Don't give up, just try a different playstyle and experiment a lot. You may find a different way to play the game that you like better than your current way.