a 5 HS refuel system would be reasonable with slow speed. mountable on Fighters or FAC's. but not too small to be abused by every warship.
I'm pretty sure this is a hard no... Steve have been very careful not to allow ANY special components that is not usable by every ship. You could argue that you could make a re-fuelling system that is say half the size but fuel 75% slower... but then every ship available could potentially use that system.
Fighter specific beam controls are one good example that was removed in C#... .Steve now introduce a half size control that only control ONE weapons. This is a good approach as you can use that on ANY ship... but in general it is a especially useful for fighters and FAC.