Piling on to this: in the few instances I've had e-Bay issues as a buyer/seller, the person on the other end has been mostly reasonable. I should think if either Amex or Paypal discerned a pattern of abuse you'd be far less likely to recieve a favorable outcome.

In any case, thank you both BugsyPal and nyc2cal! It seems the most prudent course of action will be to charge directly to the Amex. As I'm on a trip and haven't received the physical card yet, using ApplePay will hopefully not throw a wrench into things since this will be a great start on earning the bonus for initial spend within 3 months...

cheers!