Yes, it is. You will have to make every gravity well have what I will call a "beacon". This beacon is a militia-owned, invulnerable, non-moving, and invisible, trade ship. For this ability, it will have to do two casts, an ApplyBuffToTargetsAtOrbitBody which applies the bonus/penalty, and an ApplyBuffToTargetsAtAdjacentOrbitBodies with a constraint of IsCargoShip to apply the "actual" bonus/penalty to every gravity well. The beacons for every gravity well, save stars, can be spawned via a subTemplate in the GSD; for the star you will have to make a passive ability that spawns a trade ship there. Of course it is worth noting that this ability will take up a good chunk of resources, as it's being applied to a ton of ships/planets.