Custom Bootable ISO from RHEL 7.1

I have a rack full of headless servers I need to install RHEL on. Because the servers are headless, and because the servers do not have built-in DVD/CD drives I need to create a bootable ISO file that is mounted using a virtual CDROM feature. The downloaded RHEL ISO files work fine. There is tons of examples on how to extract, modify, and recreate bootable ISO files but nonthing has worked so far. Here are the steps I have tried.

Using original ISO

rhel-server-7.1-x86_64-dvd.iso

mount -t iso9660 -o loop ./rhel-server-7.1-x86_64-dvd.iso /storage/temp/ISO/

Copy the entire mounted ISO to another folder

/bin/cp -pRf /storage/temp/ISO/ /storage/temp/RWISO/

Modify

/storage/temp/RWISO/

/storage/temp/RWISO/

mkisofs -o ../new.iso -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -J -r /storage/temp/RWISO/

New ISO is

../new.iso

I have also tried mkhybrid without success.
Every attempt so far results in a non-bootable image.
Some specific help on how this is done with RHEL 7.1 would be appreciated.