aismike, I have been working on this problem for two days... got all the available driver launchers (ctload, devlod, devload), tried also my USB driver UHCI.exe..
Copying to a ramdrive was OK.
Disabling the original driver too.
But then, problems occured. Either the driver said "Unknown DOS version" (although I tried different versions) [maybe it could not find the original io.sys, command.com and msdos.sys, because they were stored on the USB stick, before the plpdisd.exe disabled it - these system files are hidden, so can not be copied to a ramdrive under ODS), or
The other problem was, that the drivers could not detect my USB stick at all (as you wrote) [USBASPI.SYS and the others]. When I tried to execute uhci.exe (usb driver too), the system freezed. Maybe there is something the original loader from plop loads into memory, which prevents to do such changes (like the extended memory driver, bc. the himem.sys can't be loaded too - error message another ext. memory driver already present, so even mscdex won't load into extended memory).
This is very strange, but I would really like to get it working. Norton Ghost 2003 detects the USB stick, even if I don't want to write the image on it, and shows the warning, that he wants to mark new drives (the USB stick). Even if I change the location of his errorlog.txt to a HDD, which is writable, it always ends with a general exception, because he want to write the "mark" information to the boot sector of the USB stick, which is read only.
If I use a new HDD for backup (to), he does not mark it either, which can lead the new image to be not bootable (the "mark" feature is not only a license protection tool, but it has a real role in the imaging task).
I wonder, why the original PLoP USB driver is not able to make the USB stick writable. It's a question to the authors.
P.S. Try to increase the RAM drive size, and load it into extended memory, if you did not (/E switch).