You can send more than three letters through VMCAS but any additional letters must be paper and not ELORS.
This was true for the past aplication cycles, but they've changed it around a little. I only know because I volunteered to do a review of this year's VMCAS. Unfortunately, though, I don't remember the specifics, but as far as I can remember, it's not as easy to have someone fill out a paper LOR this time around. Am I right, or no? Like I said, I can't really remember...
You are in a bit of a tricky situation, I have to admit, so I don't want to give too much advice because I wasn't in quite the same situation you're in. I applied to Cornell, Tufts, and Penn, and none of those schools had an issue with you sending in more than three LOR's. Like I mentioned before, I sent in 5 in order to cover all of the bases. I had my current employer/Laboratory P.I., a Vet from New Bolton, and two to three of my professors, depending on the school I was applying to.
I almost want to say that you might want to refrain from having a letter from someone that you did community service with, unless it was science/vet related. I know that sounds bad, but I had so many extracurricular activities, awards, etc. etc., and I didn't even get an interview with Penn. but then again, there are other opinions out there. I just say that because I felt like they didn't even really take all of those things into consideration in my aplication, but what do I know, maybe they did. That's just my $0.02, and it's not necessarily correct.
I think a lot of your choices have to be made on either A) what the vast majority of the schools your applying to want, OR B) what your first choice wants.
That might be a bit confusing, but it all depends on what your going for in your application. If you're looking to get a lot of interviews and have more choices, then go with what the vast majority want. If you're looking to get into a particular school, then go with what they want. Penn was pretty good about looking at additional LOR's (at least they were last year), and it seems like Ohio wil let you do that, too. So you might want to take those things into consideration as well.