Truck Groups

I would like to use a group of trucks for specific tasks. For example I would only my liquid trucks to be the only ones to carry liquid anywhere but assigning them to one specific building isn't always the most sensible thing. But if I don't other smaller trucks came take the liquid before the big liquid trucks can get anything. On the flip side if I have a dumping area and have multiple containers I want dumped but assigning trucks to one specific container is counter productive. My idea is, for example, assign trucks to a tower, empty containers into towers area and the trucks assigned to the tower will be the only ones to empty those specific 3, 4, 5, however many containers. That doesn't fix the liquid problem. But that's for people smarter than me. I'm just presenting what I think is a problem that could be fixed fairly easily.