Has this been occuring for a while now or has it recently developed? Sometimes the fad dies off. But if someone is making noise on their property in the country, I'm not sure what recourse to employ other than to ask them to keep it down. You could also ask the county what a good approach might be. Stanislaus is a "right to farm" community, but r/c planes are not usually business based. I don't see that this would seriously affect your value, however you do need to disclose this fact so it won't come back to bite you later.
Good luck to you!
Adam Dalton, Century 21 M&M and Assoc.
As for recourse, I do not believe you do. Don't be discouraged though as long as you have an agent that help you come up with a good price and can focus upon your property's key features I can't imagine your value to be "seriously" affected.
Your best bet is always to disclose.
Best of luck and happy new year.