Grub and grub4dos and maybe a few others might be able to boot to an iso file.
This may or may not work. Some odd issues go with this.
"The `yum` command shows an error message `Unable to read consumer identity`" Might be possible to change how yum accesses sources. Might be able to change to Centos sources.
Might be possible to switch over from RH to another OS from RH. Kind of like the old Knoppix install way.
I've set up pxe installs also. They work quite well.