I realized after I posted that a recommendation would probably be to update. However, due to some other rather heavy modifications to the PXE menu, other host reg questions, and even a handful or two of the php files, it would be counter-productive to take away so much automation that I’ve built up over the years. Our techs would be thrown back into manual processes until I could modify the new build to be similar to the current.
Anyway, I gave up on trying to inject ssh into the init.gz file, and instead made a wget call after host reg with post-data to a php file that could then in turn run the ssh commands I needed. ^_^ Go me.
Thanks for the time y’all took to reply, though! I appreciate it!