School Psych programs are a lot less competitive than Clinical, but you will have to prove relevant research interests and experience with kids. You'll be better off with a PhD since then you can practice privately (probably closer to what you wanted from Clinical) and also because internships in your area either don't pay or pay very little. You'd be better off doing an APIC (APA) internship as a doc student.
For more info come join us on the School Psych thread, or start one for 2016! But if you're starting one I would make it more general since most people are applying to EdS over PhDs for SP.
About Amherst, I don't know much, but they have a limited program/research interests and their website is crap. Also, it's not generally a great idea to go to the same place for PhD as for undergrad, but whatever works for you! Especially if you're not going into academia. I will say that approaching a PhD program with the idea that you HAVE to stay in one state is not a great idea, but you can probably get away with it more than in, say, a Clinical Program. You may look into UMass Boston's program, it's not super competitive to get into.