This may help someone: My GF has a UA Visa and I do not. We both signed up using her Visa as payment method but using our individual addresses and individual FF #'s. We both received the bonus for making the purchase with the CHase card. So if you don't have one but someone you know does you can still get the bigger bonus.
Unfortunately we did this with the 3,000 mile promo rather than getting in on this one.