I can support the idea of the local council. There must be ways and means of contacting them. You need to prove you are who you say you are, so need to do this in person, with photo ID. The Town Clerk or Mayor can do this, and then they sign the form, which is translated into English on it, to say they have seen you alive. You will need to do this every year. The French are bureaucratic, so a stamp is essential and the person needs some sort of title. I don’t think a GP will do, and they might charge. The word Council or Municipal are easily accepted.
I managed to get an appointment with our local Mayor just at the start of lockdown last year to do mine.