I have been using vSphere ESXi Image Builder and a ESXi config backup and use the vicfg-cfgbackup.pl Backing up and restoring ESXi configuration using the vSphere Command-Line Interface and vSphere PowerCLI (2042141) | VM…
If that is not a solution, you can clone your ESXi installation using dd & USB Image Tool, see this post: https://www.virten.net/2014/12/clone-esxi-installations-on-sd-cards-or-usb-flash-drives/