The Debian-Live approach also provides some good opportunities. First and foremost, the very easy remastering makes it efficient to run with no persistent store quite often. For instance, upon remastering, I just start without the store, and the image I run is union-mounted with the persistence file and copied&compressed. Then I have to boot something else to copy the new squashfs image in place, but that's all that has to be done outside the system.
Boot the new image without persistence, create a new persistence file.
For further adaptations, the new persistence file can be mounted in an instance run under kvm, programs can be added and settings tweaked for an eventual new remastering.
Storing the series of squashfs-compressed images, one can always go back in this process if needed.
Supermicro 4U 36 Bay Storage Server 2.2Ghz 16-C 128GB 1x1280W Rails TrueNAS ZFS
$716.98
Dell Poweredge R640 Server | 2x Xeon Gold 6132 | 512GB | H730P | 8x HDD Trays
$2549.00
Dell R730xd 12LFF 2.6Ghz 20-C 128GB H730 2x10G+2x1G NIC 2x1100W 12x Trays Rails
$721.05
Dell Poweredge R640 Server | 2x Silver 4114 20 Cores | 64GB | 8x HDD Trays
$1614.99
Dell PowerEdge R730XD 28 Core Server 2X Xeon E5-2680 V4 H730 128GB RAM No HDD
$389.99
HP Proliant DL360 Gen9 28 Core SFF Server 2X E5-2680 V4 16GB RAM P440ar No HDD
$196.95
Dell PowerEdge R720XD Xeon E5-2680 V2 2.8GHz 20 Cores 256GB RAM 12x4TB
$510.00
Dell PowerEdge R620 Server 2x E5-2660 v1 2.2GHz 16 Cores 256GB RAM 2x 300GB HDD
$79.19
DELL PowerEdge R730 Server 2x E5-2680v4 2.4GHz =28 Cores 32GB H730 4xRJ45
$284.00
HP ProLiant DL380 Gen9 16SFF 2x E5-2680v4 2.4GHz =28 Cores 64GB P840 4xRJ45
$353.00