If I recall correctly you can't have a large back pack or even a small one, the volume is too great to fit in that fighter. Also you can't wear a full set of Storm Trooper Armor, you could have the helmet and the armor itself, but not the tool belt.
Yeah, for a bit Zero, carried items counted against the volume/weight cap of the entity. Precisely because people couldn't enter a fighter while wearing a flight suit was the reason it was changed so that you could carry as much as you want, you just oculdn't drop it if it went over the limit.