Just found this thread.
I was voting for option 3 with the solenoid valves as I was reading.
I had thought about putting a tank somewhere and just charging it with rain water instead of well or city water.
I have not calculated the cost of this project.
Replumb toilets for rain/recovered water only.
Pump, tank, cistern large enough to last through the dry months.
The up side is having a water supply if there is a Hurricane.