While snooping around the stock init script, I spotted a variable, home, in the mountdata function standing out from the crowd. After doing some quick tests, the preliminary results are summarised as follows,
Prerequisite: The persistent overlay (.img, .aes or .inf) being on the same partition as the KNOPPIX file.
Functionality: Loading a specific persistent overlay at the boot time.
Usage: knoppix home=/mnt-system/foobar/dummy
*The dirname and basename cannot contain any whitespace characters.
*The basename needs to be unique if there are more than one overlay files in the same folder because the suffix cannot be part of the argument.
Dell PowerEdge R720 Server - 2x8c CPU,256Gb RAM, 128Gb SSD/3x900Gb SAS, Proxmox
$340.00
Supermicro 4U 36 Bay Storage Server 2.4Ghz 8-C 128GB 1x1280W Rails TrueNAS ZFS
$712.98
HP ProLiant DL360 G9 Server 2x E5-2660v3 2.60Ghz 20-Core 96GB P440ar
$304.35
CISCO MCS 7800 (2x) Intel Xeon @ 2.33 GHz 4GB Ram, NO HDD
$44.99
Intel Xeon E5-2680 v4 2.4GHz 35MB 14-Core 120W LGA2011-3 SR2N7
$17.99
Intel Xeon Gold 6140 SR3AX 2.3GHz 18-Core Processor CPU
$44.99
Intel Xeon E5-2697 v2 2.7GHz 30M 12-Core LGA2011 CPU Processor SR19H
$27.99
Intel Xeon W-1270 Processor 3.40GHz 8-Core 16M Cache LGA1200 SRH96
$250.00
HP Workstation Z640 2x Xeon E5-2623V4 32GB Ram 512 SSD Quadro K420 Linux GA
$234.98
HP Z420 Workstation Xeon E5-2690 v2 3ghz 10-Cores 64gb 240gb SSD 1TB Win10
$134.99