I've 3 years experience in dealing with WHMCS and PHP/MySQL generally.
As for this specific project, I have experience in customising various client area templates (css and smarty changes).
I also have experience with creating custom functionality for WHMCS, specifically a module I wrote a few years ago that required a 5 min cron task and that made calls to a third party API :)
I also have a familiarity with the Cloudflare services, including the DNS side of it (I use it for my own site).