I stand corrected again. The sheet I cited earlier even specifically states that /H loads COMMAND.COM into "upper"

found: https://www.robvanderwoude.com/command.php

In MS-DOS 5 and up, it is possible to load the primary command interpreter in high memory: […]
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In MS-DOS 5 and up, it is possible to load the primary command interpreter in high memory:

SHELL=C:\DOS\COMMAND.COM /C LH C:\DOS\COMMAND.COM /E:512 /P
This can be done by not making the primary command interpreter permanent (/C instead of /P parameter) and instead loading a second command processor high and make it permanent.
You will need to add DOS=HIGH to your CONFIG.SYS, of course.

Therefore, shouldn't this yield "best" combined result?
DOS=HIGH
DOSDATA=UMB
SHELL=C:\DOS\COMMAND.COM /C LH C:\DOS\COMMAND.COM /E:160 /P

or possibly:
DOS=HIGH
DOSDATA=UMB
SHELL=C:\DOS\COMMAND.COM /E:160 /C LH C:\DOS\COMMAND.COM /E:160 /P

There is no mention of a need to "EXIT" the primary command interpreter (is this assumed by: "/C = Close secondary session after execution of string + Also called Child process"??)?
But if I understand correctly, this places both DOS & COMMAND.COM in HMA, with DOSDATA in UMB?

I also assume the use of the "MOVEXBDAHI" option in EMM386.EXE would also save a few bytes moving the XBDA to upper memory?

HMA is just under 64kb? will all this "fit"?