The only way to win is to hire an attorney. You can't beat the ticket by rationalizing the way you just did. Another option is to ask for a deferral, although I'm not sure if that option is available for school/park zone tickets.
Did you receive this ticket in a National Park or National Forest? If you did, then the case will be heard in Federal Court and is treated like a crime. If that is the case, I strongly suggest that you hire an attorney with experience in Federal Court.
The fine for 25 in a 20 is very likely the same as for 35 in a 30. You might have a good shot at beating this, but you really should ask to contest it, and get an attorney. If the officer was that sloppy on one part, he or she may have been that sloppy in the rest of the report, and an attorney would have the experience to know which parts are essential.
The way to fight this ticket is to focus on the basics like does the speed measuring device work and did the officer lay a proper foundation for the admissibility of the result? Did the officer follow the correct procedures in filing the ticket against you?
If you try to defend yourself on the basis of saying that you were ok to speed because the park was deserted then you won't be very successful.
Having an attorney look through the case will give you your best chance to get the ticket either dismissed or reduced down to a non-moving offense.
Craig Cahoon The Cahoon Law Office, PLLC 206-795-1779 email@example.com
Unless you have proof/evidence that you were actually going 25 rather than 35, what the officer says in the statement is what will go. However, this doesn't mean that you cannot contest it. You can choose to contest the ticket and bring that information up. However, that is just facts and the judge can choose to believe you or the officer based on testimony. The best way to deal with this is to contest the tickets in many different ways, like procedurally. An attorney will be able to help you with this and perhaps get it dismissed in all.