I got to where I could do DOS 5 memory management pretty well manually.
There was also Quarterdeck's QEMM, if you wanted to go that route. (And DesqView, full preemptive multitasking of DOS apps, with good serial port support.)
I never had a problem with DOS 6.0, like many people did. As karmic payback, my initial foray into Win95 was a horrific disaster.
Something I wrote about that at the time:
Yeah, my experience with installing 95 wasn't a picnic either.
I had legacy hardware (A Soundblaster, a MPU401 based wavetable card (think small soundcard with a synth on it with a MPU-401 port on the back & a single line out jack, and a floppy drive.) Guess what Windows decided had to "share" the same IRQ (which none of them were even jumpered for?)
That, and getting some of the old DOS stuff I had at the time to run right was a trial.