Hi, and welcome to the board and particularly the Train section.
I've used the trestles a in a number of ways with trains and am fortunate that I have two sets of the loading platform accessory set plus some spare bits from safari sets. However much you have, it doesn't go far, so usually I combine it with bridge piers by LGB and/or baseboard sections on a suitable height and size.
Here are a couple of short videos which include the trestle sections on my layout at the 2022 Kirkbean Playmobil Exhibition.
https://youtu.be/Q_xn5kmrUughttps://youtu.be/OzHOhNfFXC4As you can see, I use the square flooring sections on the trestle to support the track. I've never though of using those other pieces as you have, but then I don't have many of them.
There's little to help you in the old Playmobil catalogues there is one in a 1987 catalogue like the trestle bridge you have created and another in a Victorian scene. However, these were created in a photo studio and even though this was in the days before Photoshop, you could still do things in a photo studio which cannot be recreated in the outside world. I will scan the picture and post it here over the weekend. I'll also post some of the other trestles I have built.