So, I'm sure there is already a thread out there discussing this, but I haven't found it. I know there are people talking about putting Poe Dameron in a TIE/FO, or Han and Chewie in the Shuttle Tyridium, and while those cards would be great, I think there also exists another elegant solution. A title card called:
*Stolen Vessel (Unique, Title)
You may ignore this ship's faction for squad building purposes. You may equip a second, non-unique title. You cannot equip this card if your pilot skill is 3 or greater.
Squad Cost: 0/1
While this does not allow an ace pilot to fly any ship, it does allow you to take a generic pilot from any faction and add it to your squad, perhaps a disillusioned Imperial or a Villain looking for purpose will join the Rebellion. Or a pilot tired of the war seeks to make a profit in the outer rim. Or the Empire coerces a pilot to turn to their cause. In any case, it can be thematic as long as it is limited, hence the title is unique and the PS requirement weeds out the named pilots...
I think it might also be wise to add the condition that no other unique cards may be assigned to this ship. While at first I was considering leaving this open (to have Han on a Lambada for instance), you might run into trouble when it comes to certain faction-specific characters (R2-D2) that were not made faction-specific in certain forms (astromech).
Another piece of additional text I am considering is "Until the first time you perform an attack, each time an attacker of your ship's faction declares you the target of an attack, that ship immediately receives one stress token." Kind of like Rebel Captive, if your enemy sees a friendly ship with friendly IFF's, they might be hesitant to attack until they know for certain it is an enemy (it attacks). This would bump the cost to 1-2, maybe 3, I am not certain on these matters.
Anyways, long post, but I am curious to see what you guys think of this, I also think that specific pilot packs would be cool, to put Han and Chewie as pilots of a Lambada, Luke in an E-Wing, etc. I also think it would be cool to see some Rebel Scum and Imperial Bounty hunters that could be fielded to either faction.