I agree with the guys above who think you might be better off by not doing this deal. THAT SAID, if you are all hot & bothered to get Hanley then wait for the other guy to ask for 2nd player, while setting your own limit in your own mind (martin or lowrie).
I might actually hold on to Peralta, he seems to finally be hitting to opposite field, so pitchers cant just punish him outside (like years past). In other words, I believe in the career year potential here, that and as a fellow Zimmerman owner I have ZERO confidence that he will comeback and be his usual stud self. Sports hernia surgery seems to usually zap that players power for months after. When Josh Hamilton had it in 2009, he cameback with zippy power and finished with all of 10 homers. Another reason to keep Peralta...so you can start him instead of Zim, if Zim struggles.
hope that helps...im basically saying that I would stand pat if I were you.