It can be done easily, using Creation Tools:
- For each one of the Custom Objects, use "Pivot->Affect Object Only" and rotate mesh 90º, so X axis faces towards.
- Replace the RailClone marker by a triangle, with the farthest vertex pointing to the direction you want to align the guys.
- Turn off Segment->Bend/Slice and set Generator->X Bevel->Extend to None. In this way, triangles are not deformed.
- In Forest, switch to Custom Edit mode. Assign the RC object to Tree Editor->Creation Tools->Reference Object.
- Be sure that Tree Editor->Add Items is set to "Random", and Creation Tools->Distribute mode to "Face Centers", turn on "Align".
- Turn off Transform->Mirroring (it was on).
- Click "Create".
If you want to modify the distribution, for example adding empty seats:
- Add a new item to Geometry, set it to "Disabled". Adjust probabilities if needed.
- Select all items from Tree Editor and click "Randomize".
I hope that helps. I've attached the finished scene.