I bought a vacation package that includes a car rental from Alamo. The rental is completely paid for by the tour operator (including base price plus taxes and fees). Can I still use the AMEX premium rental insurance coverage if I swipe my card at Alamo? They have an optional $1.25 CO2 Offset charge (it's an add-on that's basically a donation to clean energy research) which I could charge to the card. Alternatively I can also upgrade to a full size for about $5-10/day. Will either of these charges activate the $20 rental insurance plan or do I need to pay for the full price of the rental with the AMEX to qualify?