Let me ask you this...is your question regarding 2 more Confrontation giveaways? If it is, you can look at the past giveaways and see what kind of contributors have entered but not won and base your CV requirements from that. For example, if no one with $1000 CV is entering (or perhaps has already won), chances are you are not going to get any entries for the 2nd giveaway no matter how long you leave it open for.

If your 2 new giveaways are not for Confrontation but a random AAA title, then in addition to CV, you can do what myself and a few others have done in the past. Put a requirement in saying you must have gifted X number of games to the current version of the club. For example, 3 and 5 or 5 and 10. Whatever you think would make it as exclusive as you want it to be.

Regardless of what you decide for requirements, you have to leave it open for more than at least three days so enough people see it. And one other thing I've found regarding giveaways both on GOG and on SG is generally the more someone has given away, the more selective they are for what they want to play or win to put in their backlog. The less they've given away, the more they'll enter for any giveaway at all. Its not 100% accurate but true more often than not on an individual basis.

edit- wrong page, by accident