Just checked with the last parsec setting as well. It works.
1. Open and unlock the copy of the vehicle you have put in the inventory.
Go to the combat tab.
2. Drop character 1 in the pilot box (all weapons will use character 1's shooting skill at this point)
3. Drop another character (2) on the weapon in the "Mounted weapons" list. It will now use the shooting skill of character 2 for that weapon.
4. Repeat for the other weapons in the list.
Attachment 43096