Ive glued arduino boards to backing boards many times.
As long as everything is insulated, no part of the board is going to touch a conductor, youre fine.
Ive used velcro so they are removable and thick double sided pads many times to fix them in place for a project.
Not the most elegant of solutions but nothing wrong with it.
A slightl more elegant solution is some form of clip in frame or bracket as its better to look at and more secure.
You could always then velcro or glue the frame to the backing.
Then theres no need for cleaning the gunk off if you repurpose the board.
Gordon