If the advertisers and your ISP are cooperating there's nothing you can do. They can easily just redirect all IP packets going to their advertising partners thr

If the advertisers and your ISP are cooperating there's nothing you can do. They can easily just redirect all IP packets going to their advertising partners through some encapsulation that encodes your customer id out-of-band, encode it in to their NAT scheme, or just provide customers with static IPs and partners with regular dumps of the database.