UPDATE
A couple of odd things happened to me that may help someone else. BTW, I am preparing the USB drive on a mini running Mavericks, so some of these issues could be related to my computer rather than the process.
I was worried that I would not be able to quit the install program at the restart point, so I made a USB 2 external hard drive the target for the install data. That was extremely slow, but worth it because when the install program came to restart point, it had an automatic count down to restart and no way to close or quit the install program. I solved that by turning off the computer. From there, because the data was on the external drive, I could start the computer with the external drive disconnected to make sure the install program wasn't running.
Of course, I had to copy the install data folder from the external drive to the Macintosh HD root before running the terminal commands.
As noted above, I ran the terminal commands and it appeared to work correctly, but my Finder was reporting that Applications/ Install macOS Mojave had only 22.8 Mb. After some checking, I decided to copy the folder onto a spare drive and found that the copy had 6 Gb registered during the copy process. After the copy completed, it reported 22.8 Mb again. Strange.
I decided that the data must be there, even if not reported, and I went ahead with Unibeast which completed successfully. I hope this helps someone else if they run into similar issues.
Now it's on to try installation.