Have you checked all the options here? https://docs.grabaperch.com/perch/configuration/database/
If there's something you need to be able to set but can't, we're just using PDO so it should be easy to add.
Thanks for the thoughts above. The situation is that Perch and Runway under the current license model do not generate enough income to keep me working on them full time. Progress on v4 is slow because the time I can afford to dedicate to it is…