a few thing have been said about the goodies collected after a supply mission.
dont know if there is a max inventory on the manticore or not but heres my idea
have the choice or depositing items in the manticore or having a supply transport come to the site to pick up the items you dont want.
this could be represented by a little icon on the geoscape flying to the site and back again.
this could also add a new mission type that the transport could be targeted and brought down, this could result in a rescue and salvage operation. it would be a random encounter so it wouldnt happen every time, maybe if its flying in the mist zone.