Re: Changing config from a %post?

What's the proper way to fix this? I can update the package to create a user and use it in the default config, but is it correct to have a %post that changes the existing config (something like a "sed -i")? I'd also like to switch it from running in daemon mode to foreground mode (and change the systemd unit to match), but again, that requires editing the config; there's no command-line option for either of these. I'm not sure of the "best practice" here... as a system admin, it feels wrong to have RPM scriptlets editing config, but I don't see another way forward, short of modifying the program to accept command-line overrides for these options (which has its own "fun").