I think you should reference this bug that should be in fact 2.
1 - need to have multiple cert supported because reaching the limit of 100
2- need to support dns validation
https://bugs.koozali.org/show_bug.cgi?id=11796I know how to code PHP but Perl is not my World, ...
well you are lost there because dehydrated actually uses bash, not perl.
1/ for the multiple certificates
you could simply disable the 90 or so domains from lets encrypt and only enable the 4 you need. LE contrib allows to ask for all host/domains, all domains or only selected host and domains.
then you could either use the sme way to add a custom template fragment to /etc/dehydrated/domains.txt with a line containing only your wildcard or your list of 90 subdomains
2/ for the dns part
you should first check what is your your dns provider and what hook you should use, then configure the needed tokens on its website. then configure the appropriate hook. then call it in the basic hook script we use.
you could configure the dns challenge for one domain only by reading the documentation of dehydrated whic state you can add a dropin config in /etc/dehydrated/certs/yourdomain/config and say there you want to use dns validation.
remember that our dehydrated configuration has been thought dor standalone automatic renewall. you can not pause a cron waiting you to inpit something elsewhere and resume the script.
if you want to renew manually then create your own config and domain.txt and point them using manually the cli to renew manually those domains.