I haven't done this,m but this is the route my son is going.
In my opinion, if you are going to email coaches you have to have something interesting to say. I'm a 2020 who pitches 85, or has a pop time of 2.0, or runs a 7.0 sixty yard time, or hit 2 HR's on my HS field last year...etc.
I don't think the approach of "I really like your school, but I'm not very good yet", will get you anywhere.
As much as people say camps are a waste of money my son enjoyed the one he went to. He sent the coach an email prior to going, got to see the campus/field/most of the staff, meet some current players and the coach remembered his email. It was less than $150 and at least let my son see the place and the staff, seems worth it to me.