Can the 50 ft. Butyl Sealant Tape Roof Accessory be used to seal RV windows?

If the intended application is putting it between two faces (installing a new window for instance) then it works.

Depending on your desired application, if you are wanting to seal an already installed window, no it is not recommended. However, if the intended application is putting it between two faces (installing a new window for instance) then it works. Butyl tape does not have a backer side that doesn’t stick so it can be left exposed.