First off, welcome to the addiction, if your not already you will be. It's a great place to be too.
You can safely paint your backer board. Then glue the art work on top of it. I do the same when I am using felt for a backer and have not had any issues. Just be careful with the glue and squeeze out some can be a real pain to clean up. Feel free to ask any questions, there a lot of great folks here willing to help.