Yes! Perfect! Thanks, Sijmen. I completely forgot about the Option
selection of the MyIDE menu!
I actually got it all set up perfectly with 3.5F. I also got Hias' patch to run as autorun.sys using MyDos 4.50 -- would not run as autorun.AR0 with 4.55 B3. Not a big deal, but nice to have everything "perfect!" 4.55 B3 is a very good version of MyDos, but 4.50 is still the most compatible, I think.
This should be an option in the MyIDE-menu to disable screen-activity.
After changing the OPTION_byte, you need to save the new partition-info to IDE.