Those are good suggestions HMPS but I re-read the OP and this will be a major obstacle to even use the GCs as CCs:
Even though I was able to assign the PIN number by phone, I could not activate the card without speaking to a 'customer representative'.
UNLESS cards are activated, they can't be used as payment so that if let's say, insurance company is willing to accept CCs for auto/home premiums, these unactivated cards will not go through.
NEPony may not have other options but call and speak to a rep. Hopefully, the rep is cooperative and willing to help.