I do it all the time. Just add it to steam as a non steam app and select the proton version you want to use. It will run just fine.
EDIT: If you need to install first, just add the installer as a non steam program, run it, install normally and then chang the path of the exe and the working folder to those of the installed game
I’ve been installing dodi, elamigos, fitgirl repacks for a while and still have to find one not working. Dunno what repacks are you installing.