I do this too. After throwing around a bunch of other ideas, I realized that a Pi is cheap enough and the one-shot cost is nice. If it dies, I just update the MAC address for its DHCP reservation to the new pi, spend 10 minutes setting up a new instance, and that's that. It just ends up working.
The dream is to network boot the thing, so you literally plug a new pi in to network+power and it automatically boots and starts running stuff:) (Well, a Pi also needs a 1-time step to enable network boot, but still)
That should work as long as SD card is okay. Unfortunately, it's my understanding that SD cards remain the most likely thing to fail in the entire system, hence my interest in not using them.