I get the idea that the loads out/back idea works them through the mid divide of a table layout (forgive me being dumb we use table layouts extremely rarely if at all here)…
For point to point or even round the walls with staging tracks on one side you might like to think about the following.
(Sorry don’t know how to post a sketch0
If you plan a line A - B - C with C being the plain junction (with no loops, spurs or sidings) to D and E…
If your layout is whatever is at B but deliberately not suitable for switching in or out of your longer trains…
then traffic for D form E must go to A to be switched before coming back and vice versa.
it doesn’t matter whether the cars are loaded or not they travel the same through B either way.
The only thing you need is pairs of numbered cars… and to atch the weathering on them.
just a thought…