Sorry I'm late to the party, but here are a couple of things to consider:
A) Are you paying for your water, or does HOA take care of it for you? If you are not directly paying you will not see as much benefit as other Rachio owners.
B) While your old controller was designed to be installed next to the valve, Rachio can be installed further away or even inside. You only need two thin, low voltage wires running from your rachio to your zone solenoid. Perhaps it will be best if you install your controller inside (where wifi signal is steady, someplace close to your power outlet) and drill a small hole for the zone wire to get out through your stucco, make sure you drill away from the power outlet, at least an inch lower than the bottom of the nearby power outlet (to greatly reduce a chance that you will drill into anything important). Small hole can be easily sealed for weather proofing and repaired if you ever need to remove your system.
So, don't worry about long zone wires (they are designed to operate much further than what you need), install Rachio where it is convenient (or possible with HOA) and use / run / bury two zone wires needed for your solenoid.
Should you choose to stick with Rachio, this Hunter AC valve (link) looks to be a compatible replacement to the DC solenoid you are using. Should be pretty forward / easy replacement.