I've found killing the appropriate PP enemy far quicker, cheaper, and more fun. 30 merits per kill, no notoriety or bounty/wanted status (Ok, you get a PP bounty, but that's different).
Just head to a nearby PP enemy control system or system they are trying to expand into and kill the right ships. As an independent...
VS Aisling destroy Campaign Ships and Aislings Angels
VS Duval destroy Imperial Supply Ships and Imperial Enforcers
VS Denton destroy Imperial Support Vessels and Imperial Warships
VS Zemina destroy Private Security Ships and Torval's Brokers
VS Zach destroy Federal Logistics Vessels and Private Military Contractors
VS Winters destroy Federal Couriers and Fed-Aid Vessels
VS Antal steal Utopian Dissidents (from Reform Ships) and Supplies (from Messenger Ships)
VS Delaine steal Marked slaves (from Kumo Crew Transport Vessels) and Unmarked Military Supplies (from Unlicensed Trade Vessels)
Pick someone you dislike and go at it.
Note: Credit for this goes to the PP Guide that I would link you to if I had kept a link instead of screen grabs. It's bound to be in the PP subforum somewhere...
Edit: Undermining and stuff what you need to know: witch ships to shoot, ...
https://forums.frontier.co.uk/showthread.php?t=153464