I considered it, and that was in fact in the original plan. However, it'll be easy enough to leave the Liberty ships at home when we have to supply Bonn Station, as anything we do in Rheinland is greatly limited anyway.
Since Bretonia and Kusari don't have any issues with Liberty ships, and there's next to nothing we're legally allowed to do in Rheinland to begin with, I didn't really see any good reason to keep Liberty Civilian ships off our list. Note that we're still not using the guns, even though the rules say we can; there's a sizable difference between military weaponry and civilian freighters.
To be honest, I haven't exactly figured the details out - I'm taking any ideas.
But the basic concept I had in mind was a monthly fee that could include free or discount ICS escort and partial compensation for repairs and lost cargo so long as we can be sure that the pilot wasn't at fault.
One definite point is that it'll be a factions-only deal - unofficial factions qualify so long as they have a clear forum presence of some sort (unofficial message dump, diplomacy I can reference, anything really) and an easily recognized tag. And of course there'll be some restrictions on the deal... which our Investigators will make sure you're following.