I have gone through your requirement. I can do this. I have more than 10 years experience in PHP including 4 years experience in WHMCS. I have WHMCS development license.
Relevant Skills and Experience
My WHMCS addons
CRM addon, Refer a Friend addon, Softlayer addon, Partner addon, Server audit addon, WHMCS Vtiger bridge, LibreNMS addon, WHMCS freshbooks bridge, Cloudways provisioning module etc.
Proposed Milestones
$100 USD - Advance (Initial payment to start work)
$150 USD - After completion of the project