Can you substitute kdm for gdm in CemtOS 7.3?

[desertcat]

Well I am still fighting the fight to see if I can somehow stop Xorg.0.log from chewing up my /var /log file.
Question: Can I substitute kdm for gdm (since I am am running KDE not GNOME) or am I stuck with gdm?
Question: Is the "new and improved" update for /var/log/Xorg.0.log which started this whole problem a problem independent of the display manager, or is it linked?
Question: Failing everything else can one run /var/log/Xorg.0.log as a CRON job, so that once it reaches either a certain size or after a certain time it can be log rotated?
This really is an annoying problem that needs to be fixed.

[TrevorH]

Perhaps lightdm might work? I use that with MATE but I don't know if it would work with gnome3.