Dilemma HO layout plan

[faraway]

That looks very good but I do not fully understand how you will run an operating session.
Where do you start a new operating session with an engine and some cars to be distributed and where ends the session when all car are collected?
The tracks at the top right end would be useful to attach a cassette with a train for that purpose but the mainline is at the very bottom and hardly accessible to add remove cars.

I will stage the train at the start of the session. Probably 3-5 cars.

Sorry for expressing myself so poor. That is what I assume but my question is where do you stage those 3-5 cars at the beginning of a session?
The best prototypical track would be the mainline running at the very bottom and hard to reach. The tracks easy to reach with your 0-5-0, e.g. the cement transfer facility, are not the best starting point for an operation session.