I think you don't need to use the lower of your two sidings to assemble outbound traffic, if I've understood your plan correctly. Here's my take on it (but I'm no expert!):

1. Train arrives

2. Loco runs around

3. Detaches brake van and places in the run around loop (or at the end of the line)

(Inbound traffic at this stage still coupled to the arrived train)

4. Outbound traffic collected from the sidings and assembled onto the brake van in the loop. There are constraints on the marshalling order, which wagons go where.

5. Inbound traffic collected from the platform line and placed in the sidings as required

6. Loco couples to passenger coach draws runs forward and reverses onto the wagons and vans in the loop to assemble whole train

7. Whole train drawn out then reversed back into platform line ready for departure

Good to be thinking early about operations. I'll too look out for Stationmaster's advice.

Ah, yes that would be a simpler way of doing it, thanks.