An unpopular opinion: The only GTA server where college RP has thrived is GTA:W - They've have had 30+ players online, every night for nearly 2 years. The only factions that come close to that are PD and SD, not even FD matches their numbers, so they must be doing something right.
Rather than try and copy a faction that didn't work (USALS), it would make far more sense at taking what this faction did right and then see how it can be improved.
The main issue is always going to be the lines of where acceptable criminality is drawn and I think you are on point when you said this:
And obviously - it should be a crime-free zone on OOC level, BUT certain small crimes should be allowed for students only (acts of vandalism, small drug deals, fights, etc).
This statement is absolutely how College RP should be - expressly around campus. As far as I know, this is how ULSA mostly operates on GTA:W
- However GTA:W has a very strange notion of illegal factions vs legal factions - I think ULSA and any other faction is forced to play into this by their teams Legal Faction Management & this is where the cracks occur.
The problem of Illegal vs Legal faction divides.
There simply should never be a divide. You can have corrupt cops, you can have students who are borderline psychotic, and you can also have people caught up in gangs that aren't terrible murderers - there should NOT be a Legal / Illegal faction management, there should just be 'Faction Management'.
Remove the divide and suddenly you open up for far more 'grey' area's that can lead to interesting character concepts and there being a far less black vs white take on Legal vs Illegal RP. (Also I think one of the reasons previous GTA:W servers are so incredibly toxic).
Crime
GTA:W aside - What I think we'd certainly agree on is that you can't have daily stabbings / shootings in high school or college RP or it just reduces it to the very worst of Davis RP and it will kill the faction off just as fast as your average gangbanger_01 faction.
While some serious crime does occur at college campus', it's extremely small in number and murders are even more rare.
Conclusion
College and Highschool's should be Mostly considered a 'safe zone' - where fights should be restricted to brawls and the most regular crime being drug deals (as per the posters comments above).
