We bought ours from Loren at XGrid. It was a very pleasant experience and I'd definitely recommend them. Unfortunately, we aren't anywhere near San Diego, but I believe the Summit we looked at at XGrid towards the end of last year was sold to someone in the San Diego area. Maybe Loren could hook...
I wonder if the digital version of the thermostat would work better. It looks like maybe it's in Celsius only, so perhaps that's why it's not offered as an option.
https://www.justkampers.com/us/propex-heatsource-digital-thermostat.html