Sorry, but you are wrong with some statements about Steem.
A is not always the boot drive in Steem. It can 'boot' from mounted 'hard drive' too. But TOS actually will set as default drive C for instance only when boot from C is successful (actually driver needs to do it). Steem will load AUTO, ACCs etc from C (GEMDOS emulation) after warm reset. So, not after 'power up'. You need to click with right mouse button on reset icon for it. And must check on 'boot from hard disk' too.
It means not that your proggy is useless. I just like to clarify things and correcting errors.
And when we are about Steem and it's hard disk emulations: there are cases when GEMDOS emulation of hard disk - so mounting some DIR of Windows (Or Linux) as Atari partitions fails : for instance games Shadowgate, Deja Vu 1 & 2 and Uninvited work not from GEMDOS emulation, only with real hard disk emulation, so with Pasti and hard disk image. The reason is that Steem uses some patching of TOS GEMDOS filesystem by GEMDOS hard disk emulation - it works in most of cases, but not always.
I guess that there are some other SW too which needs true emulation - Petari's game adaptations for instance (where F15R files are present). + others ...