I have created a covered hopper for all your plastic pellet, suspicious polymer, grain and granularized product needs. In addition I have also reduced the skins for the C36-7 to just the 2 for now, since I don't feel like making more skins for it at the moment.
I tried to make the open-door freuhauf trailer hollow, but despite my attempts, it would not work. If you want it to be usable as cover, you need to disable the collisions and build around it.
