Could a spray adhesive be used ? It says it's ozone friendly and no chlorinated solvents, designed with the environment in mind on the package.
i don't know about your spray-on, but gorilla glue is used as an alternative to silicone. you should search this site for "silicone" to find more info.
Yeah I have some of that.But it seems expensive to squeeze a bunch of that on the background then use a paintbrush to dab it everywhere to cover the back.
You might want to see if it is recommended for high humidity applications.
I would call the company and see if it is totally inert once it is fully cured, otherwise you run the risk of it leaching some nasties.