As stated above, silicone conformal coating is made for this application. Spray or liquid form will do. Many come with a UV indicating dye so that you can see if you have complete coverage. It is flexible, repairable, and wont cause problems with components. If you cannot locate it at an electronic supplier, sometimes a similar product is available from automotive part suppliers, same use, waterproffing electrical connections on vehicles.
Here in Canada, a 340g spray can is about $18, quite abit of caoverage from one can.
here is a link: **broken link removed**