Ask your question and if you experience any problems use the maintenance tips button to send me a quick note about it. Just put your email in and you will see where to report any problems(comment section).
I should be able to send you a response back to your question pretty quick. Usually with a few minutes. But no longer than a couple hours.
Please have your project up and going.
You may not need the surface mounted box here if you are flush mounting the GFCI. The picture shows it flush mounted 15amp GFCI. A regular cut-in box will work if you flush mount. Make sure you use a 20amp GFCI.