I remember the pain of trying to get just that last few bits of LMA necessary to get "Frontier Elite II" working. IIRC it needed something like 600k out of the 640k to be available, something that was nigh on impossible with the standard MS-DOS mouse drivers available at the time. They'd take up some 20k or so of the LMA, leaving my system at about 590k of free LMA, no matter how you tried to get them to use UMA.
I got given a mouse driver by a cousin who'd bought a new mouse that came with a driver that put most of itself in HMA and only a couple of k of LMA. That finally made it easy to have sufficient RAM left over.
I had a few minor issues with that driver, so I'd keep two copies of autoexec.bat around, one for when I wanted to play Frontier, and one for when I wanted to do anything else.
I got given a mouse driver by a cousin who'd bought a new mouse that came with a driver that put most of itself in HMA and only a couple of k of LMA. That finally made it easy to have sufficient RAM left over.
I had a few minor issues with that driver, so I'd keep two copies of autoexec.bat around, one for when I wanted to play Frontier, and one for when I wanted to do anything else.