I would exhaust all the kaplan practice tests, then aamc test. AAMC test usually give a great ball park, especially the last three. I mean you can def take ones that are being administered now but you won't get a score, so there is really no way to know how you did.
I WAS planning on doing the same as you are thinking but decided against it. for the following reasons: 1) You really can't predict how you did on the MCAT without getting your score back. 2) For this cycle of MCAT (current version, not the 2015 MCAT) you can only take the MCAT up to 3 times. The void MCATs count as takes. So you would only have 2 tries (if needed) to get the score you want.