How to start composition manager compton on start of xrdp session?

[charlweed]

Background: I’m trying to work around the issue where javafx applications fail with the error “Can't create transparent stage, because your screen doesn't support alpha channel. You need to enable XComposite extension.” Accordingly, I’m installing an XComposite extension.
I have centos 7, and my windowmanager is KDE plasma.
I used yum to install compton 1.1. Now I want to configure compton, and have it start when I connect with an xrdp client. I have found no man page for the compton configuration file, and nothing about having it start automatically.

Thanks!