Is this campaign file password protected? Simple protection should be fine, but this way players can't just add their own stuff in without your consent, or change the way the campaign is structured. This way if you happen to play with someone that say fudges the rues some, it will be harder for them to do.
I've considered this, and I wonder if it is appropriate to place anti-cheat responsibility with Redblade. I would prefer clearly indicating what aspects of a character have been customized opposed to coding all sorts of physical restrictions.
Redblade will probably contain a special window that lists all notes, customized topics and 'illegal' selections (like when there are more skills selected than normally allowed, or when the prerequisites of a feat are not met). Printing this data on a character sheet (extra page) would be possible.
If you do not trust one of your players, just have them send back the character file to you, so you can inspect it and print it out using your unmodified campaign file.
Can you determine what rolling methods are allowed in the campaign file? Is there a way to make Global changes to the campaign file? Add a 7th stat. Add other effects all characters get from said stat. Start everyone at max funds without going into each class file. Start everyone at max HP. Basically anything that would be in effect campaign wide, and not just on one character or class.
Answer to all of these is: probably. I'm trying to make things as efficient and intuitive as possible.