So I've tried a few things so far.
First, I tried to use the 'free' version of LaunchControl but you can't save or clone or really do anything except view information. So, paid the $31 to get the actual tool.
try was I created a shell script in /usr/local/bin that did nothing except "ls -lsatr xxx" on the mounted drive and a single file. I at first cat'd this to /dev/null. This didn't seem to affect the drive which eventually was dismounted.
Did the same thing except this time my "ls -lsatr xxx" output goes to a hidden file on the mounted disk. So far the disk has remained mounted. The real test will be overnight when the system is more or less idle. I'll report back tomorrow.