The First Officer position is a Job and I still dont understand why do u want to pay to work ?? Especially knowing when you are not going to benefit by what you are paying for. Just look around .. there are plenty of KFA FOs with 1000 hours on A320/ATR72 experience on type with out a job what are you going to do with your 300 hours on A320 or 737 ?? No airline would even consider you if they come to know you are one of those P2F guys. If you are serious about aviation and dont have a job yet utilize this time to clear your ATPL papers.
ps. There are good chances an airline will consider you with ATPL papers cleared more than the pay to fly fellows.