I would personally recommend only doing three PM&R rotations max, including your third-year elective. A couple of attendings at different programs said they thought three was really the maximum number of PM&R rotations a student should do--there really isn't much to gain by doing more electives, and you lose out a lot on a broader education. The attendings were speaking about one-month electives, but the same attendings also told me they don't interpret students who do the two week electives to be as serious about the program as those who do the one month elective. Two week electives are really more for students not going into PM&R to see what physiatry can offer their patients. That, and to entice them to convert to seemingly now less secretive cult of physiatry
I think with your home rotation, two away rotations, club president, 3 annual conferences (especially if you've been making contacts at them), and research experience will more than adequately demonstrate your interest in PM&R. I would imagine if your scores are good, you would likely get offers from the top programs. Hopefully some residents/attendings can chime in with their opinions.
On the other hand--you should never take someone else's advice if you're going to regret it later on, so if you're really set on doing 3-4 away rotations, then just ignore me