"Enable crossfeed" button needs balance

[ezsnackeur]

Enabling crossfeed in the PAW for a part that defaults to having it off (eg. decouplers, booster tanks) should come with a weight and cost penalty to represent the added complexity of the system, at least it should add weight and cost equivalent to an external fuel duct, although the external duct is too cheap and light as well right now.
Considering how difficult to implement and rare crossfeed is on IRL applications it should be a huge nerf tbf.