FYI - it is illegal to have a Preview before March 29th - better not let OHSAA see this thread! Looking at your schedule though you could get by with calling it a scrimmage as all teams play within the allowed three hour window for a scrimmage.
This is a letter I got back from Roxanne Price when I asked about a preview on March 23rd:
Hello all:
There is actually not a date indicated for scrimmages or previews in the Ready Reference Guide, only a reference to beginning after practice. An asterisk should have been placed next to previews, just as it was for the other sports which permit previews. The “regulation” regarding Previews has not changed, “beginning with the Friday, before the season begins and ending with the first regular season game of the teams involved. No Preview can be played prior to March 29, 2013. The specific dates are mentioned in the Softball Regulations as well as the OHSAA Handbook. It does not have to be on March 29, but cannot be prior to March 29.