I think our primary aim in S-13 would be to stop the Military goods being exported towards the Taus when Rheinland needs them more. The Kanzleramt approves of such trades, so opposing this export would be a blow to them aswell, not to mention the weapons of aid we gain from such an activity. Give the weapons of the people back to the hands of the people.
Also, remember when the Sails introduced a claim for Nuremberg? We encountered that on our RMs, but a large portion of Hessians also witnessed it. I believe shooting down the Corsairs in S-13 and 19 (and keeping them away from Rheinland's northern side at that) would decrease the chance of such claims being introduced and God forbid, fulfilled.
Another reason to go to 19 is the Hawaii. It's pretty much a drug hole, a chief point of cardamine distribution. It's way off the RM's ZoI, but has an effect on Rheinland, especially if the cardi shipments become "looked over" by the Rheinland lawfuls. Thus, the prevention of cardamine distribution could be managed by the VF pilots.