The German "Verein zum Erhalt klassischer Computer eV" published their annual club-magazine.
LOAD issue #11 can be downloaded as PDF from
https://www.load-magazin.de/load11/ - please search for "download", as I do not want to share the file's deeplink
Starting with page 50, there is an article about how to use a NeXTstation without monitor.
This seems like a nice, detailed article with details like how to make a cable for serial port communication, although I'm guessing a bit because I don't know German... (less of a problem though than it was in 1992). My first experiences with NeXTs were all headless, albeit over telnet, so I appreciate this style of usage :-)
Some very basic information along these lines can be found in answer 5.39 of the NeXT FAQ (https://www.levenez.com/NeXTSTEP/faq.html).
That seems like a nice magazine. 96 pages! And the fact that it spends two pages on the PERQ earns much respect from me...