That's an excellent idea, as always, darkom.
I'd love a way to do this without the other side knowing, that sounds very interesting! However, it might pose issues as to us actually finding each other, no?
I'm on both sides too, as is Broken-Scale, however I'm sure we can both keep our lips sealed.
Well, the way it works is our discussion forums would be password locked, so only the people with their side's respective passes could view the threads. The IC thread is still open here, so both sides could view what's going on there, but future plans would be hidden. Also, we could leave out certain vital facts to prevent the other side from knowing, but assume that our characters spoke of it during a timeskip. Like a "You know the plan?" situation.
The whole idea is that the other side doesn't know our every move. They can, however, follow us, to a realistic extent. Obviously they'll be close enough to follow our physical tracks; it's hard not to leave footprints in the mud, afterall. They'll also have native sightings to go off of, as word of foreigners tromping through the swamp should spread fast. No, the hunters should have no problem following the prisoners, unless we pull some of the tricks out of our sleeves (I have a few in mind already). The prisoners main weapon will be their speed and head start; our only hope will be to just stay as far ahead of the hunters as possible until we reach Morrowind. We can throw them off the trail and whatnot to slow them down, but lose them entirely? Not likely. No, it should be an exciting chase all the way to the northern border.
And as to the people with characters on both sides, I think they can handle not giving away the other side's secrets. If you two submit ideas though, you'll have to do so fairly. You can't, for example, learn that the prisoners will be heading off to a certain town, then go to the hunters and say, "Hey, let's go to this random town for no real reason." Of course, I wouldn't expect that from either of you, so we should be fine.