Definitely they're holding upgrades until the last minute. The phone agent confirmed there were 20+ F seats to sell a day before the flight.

But the good news for 1P and above on Hawaii flights is your upgrade will clear as there are not that many elite members on these flights AFAIK...

So, I think you could use either CR1 (which does not convert to miles) or e500s whichever depends on the expiration dates.