You probably already know this, but just in case and per many TFP threads, there is little to actually worry about unless you're concerned about chlorinated (and/or saltwater) running off the deck into vegetation. So no flood worry because once the water level reaches the deck it just acts like a solid deck and runoff goes where it goes, just as it does with fun splash-out. I only mention it because some folks are concerned that the whole pool will suddenly drain and of course that does not happen. So the only real issue is skimmer function, since it cannot skim with the water level above the top of the skimmer (ie skimmer flooded).
I agree with
@ajw22 that any system of sensors and valves (and pumps for that matter) would probably become an unreliable maintenance headache. But I have two other ideas. If you have a camera on the pool you could set up a remotely operated valve tapped off the pump outlet side that would act to drain off water. Many folks without a passive overflow pipe will just use a manual drain valve, so how to automate that? A simple remotely controlled valve (Jandy, whatever) should work well, "I think". I was going to suggest a spare irrigation valve/zone but I'm not sure that is safe and per code, as the 24VAC solenoid may be an issue even though it's fairly well isolated from the water. Anyway, easy enough to remotely open a 12V Jandy valve while watching via camera. After a few experiments, you'll know how long to allow the valve to be open, or have it on a 10 minute timer.
In other threads folks describe adding a small pipe into the side of the pool, sealed to not leak, in a spot that won't be noticeable (or it just looks like an outlet nozzle), set that out into the yard, and the outlet adjusted to the perfect level just before waterline floods the skimmer. That's of course the same way a skimmer-based overlow pipe works.
I'm wondering about another idea but
I lack knowledge of fluid dynamics. If you were to add a tee below ground in the skimmer line and ran that up in a "standpipe" to the perfect level, would the pump suction drain that pipe before taking water from the skimmer, thus losing suction? I think that might fail and be dumb, but I simply don't know! One might be tempted to add a check valve in that case, but that too could fail causing suction of air, and I'm not even sure the force of overflowing pool water would be adequate to open the check valve to drain, presumably when the pump is off. There are some check valves that require less force, just sayin.
Enough with crazy ideas - that's all I got - Good luck!
