Thanks Chris, I appreciate you can't give an official response.
My main confusion with whether it's A or A-EP is when going through the wizard to establish which questionnaire is applicable. To get to A you would have had to select option that says payment option is fully outsourced, which doesn't sound right when the customer is on our site.
For the A Questionnaire, there is this line:
"All elements of all payment pages delivered to the consumer’s browser originate only and directly from a PCI DSS validated third - party service provider(s)."
How does the WHMCS/Stripe solution fit with that line considering that the the customer sees the WHMCS checkout page with Stripe pop up window?