Overriding default states for a taskexecuter

Ladies and Gentlemen,
I am trying to implement a model involving tugger operations in the warehouse. In my model a tugger and each of attached carts are a separate instance of a taskexecuter.

The problem is that since the tugger is not transporting any flowitems it is stuck in the state STATE_TRAVEL_EMPTY, regardless of what it is doing.

I tried using setstate() as a part of my task sequence, but the state gets overriden as soon as the proxytask TASKTYPE_TRAVEL kicks in.

I need to collect the state data separately for the tugger traveling on its own, traveling with loaded carts, and traveling with empty carts, so just moving a dummy flowitem into the tugger to force a switch to STATE_TRAVEL_LOADED will not solve my problem.

Also, is there a way to execute a trigger on a state change?
Thanks!
V.

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