JJeffrey - For this to work do you need to book Main or Main Plus or either should work? It looks like the only difference should be the below if I'm following so Main would be fine if you're willing to have the amount paid with the credit card be converted to travel credit. Let me know if the below seems right:

1) Main - full refund to trip credit. So if you pay $180 with trip credit and $5 with credit card, the entire $185 goes a new trip credit
2) Main Plus - full refund to original payment method. So if you pay $180 with trip credit and $5 with credit card, the $180 goes to a new trip credit and $5 goes back to the credit card

Thanks!