I don't give up easily, so I pursued the idea of using remastersys even though fragadelic predicted that it might not work in my situation. I found a discussion on upgrading grub legacy to grub v2 here: https://help.ubuntu.com/community/Grub2
. I followed the instructions and sucessfully upgraded to grub v2.
I stumbled quite a bit with remastersys because I knew that I wanted to customize the "isolinux.cfg" file but I wasn't clear on how to accomplish this. I was using the GUI and first tried to simply put a modified isolinux.cfg file in the /etc/remastersys/customisolinux folder. I did not realize that it was necessary to copy all
of the files required for the isolinux folder into the customisolinux folder. Ultimately, this resulted in an error and a failure to build the *.iso.
I have since learned that for my purposes it is better to execute remastersys from the command line within a terminal because then remastersys can be separated into a two-stage process with the first stage building just the "ISOTMP" folder if invoked with "sudo remastersys backup cdfs". Remastersys can then be invoked again with "sudo remastersys backup iso" which will calculate the "md5sum.txt" file and create the *.iso file.
Inbetween these two invocations, the contents of the /home/remastersys/remastersys/ISOTMP/isolinux folder can be freely modified to change the isolinux.cfg and splash.png files and to add other files to the isolinux folder, such as reboot.c32, poweroff.com, etc. When the command is invoked the second time to build the *.iso, the modified contents are carried forward into the *.iso which is being built.
After considerable experimentation, I suceeded in creating a backup image that I'm pleased with. I have attached a crude screen capture of my menu to this message.
Remastersys is a truly remarkable script even if initially it seems rather complicated for novices like myself. I applaud fragadelic on his extraordinary work.