It depends what you need to do in particular. If the only traffic categories are “RDP” and “the rest”, you can selectively exclude from fasttracking the RDP traffic, handle it by the queues chosen by packet-mark, and handle the rest by the queues chosen by absence of packet-mark.
You have to use one queue tree on each interface, which handles only output through that interface, because in order for a queue to handle fasttracked packets, its ultimate parent has to be an interface, not global. You can reuse the same packet-mark values in all of these trees, i.e. you can assign the same packet-mark to packets in both directions of the tracked connection.