You got a lot of dedication to get this mod going. Besides docking with wrecks as a way to learn new ship types, it might be interesting to have a chance to learn ship designs by docking with wrecked stations, eg, Sung Citadel's give wind slaver schematics, ranx fortresses give ranx gunship plans, dwarg fortresses give xoanthrope raiders, etc. Ares shipyards can yield sandstorm plans.
Fuel is a good trade-off, but another thing you could consider is trading ore and armor plating to be processed into ships. That would cause a balance between selling ferian/outlaw miner loot for rins, or trading it for escorts.
Summoner/Carrier Mod
From the transcendence main page:
This is how I have introduced my dockscreens in my star carrier mod. It might be a little neater than the virtual useable item you are using at the moment.<PlayerSettings>
shipScreen="{unid} | {screen-name}"
A player ship may specify a custom ship screen. This allows the modder to override the screen that comes up when the player presses thekey.
Yes, I really like the idea of customizing the player's ship screen, but I don't like the fact that it can create conflicts with other mods. I prefer my mods to be totally self-contained. No dependencies, no potential conflicts, etc.