The by-law that you were charged under is Ajax TRAFFIC BY-LAW 5-2004 section 9.1 (o) which reads: "No Person shall on any Highway Park any Vehicle between the hours of 3:00 a.m. and 6:00 a.m."
-So to answer your question about whether you can be charged with this offence on an unincorporated road we have to look at section 1.1 of the by-law to see if the definition of a highway includes unincorporated roads. Section 1.1 indicates that the by-law uses the same definition of a highway as the Highway Traffic Act. So we have to look at section 1(1) of the Highway Traffic Act, which says "highway" includes a common and public highway, street, avenue, parkway, driveway, square, place, bridge, viaduct or trestle, any part of which is intended for or used by the general public for the passage of vehicles and includes the area between the lateral property lines thereof; ("voie publique")." By this definition it looks like the unincorporated road does count as a highway, so the by-law is enforceable.
Here is the links to the by-law and HTA if you are interested:
http://www.townofajax.com/Asset190.aspx http://www.e-laws.gov.on.ca/html/statut ... 0h08_e.htm -I think the only reason they put the "unincorporated road" sign up is to tell drivers that the road is maintained by a private company and not the city, it is basically saying if there is a maintenance problem with the road call the private developer not the city and if poor maintenance causes an accident sue the private developer not the city.
-As to whether you can ask to have the ticket reviewed, you certainly can, although I dont know whether they will reduce the ticket or not. Here is the link that tells you how to do that http://www.townofajax.com/AssetFactory.aspx?did=9125
-Im not sure how long Ajax takes to bring people to trial, someone who lives there would probably know better than I. Also remember that parking tickets do not affect your driving record, so you will have to decide if putting in the time to prepare for and attend a full trial is worth it for a $25 fine.
Anyway good luck and sorry for the long winded reply, hopefully some of it was useful.