Any recommendations for how to best implement the ability to restrict the number of records a member can submit to a custom CMS database?

I'm looking at possibly a code hook, but I'm not sure the best method to override.

The use case is certain member groups being able to submit records to a database, but each member in the group can only submit 1 record. I want to make sure they can't submit multiple records or edit any records but their own.

Short of putting a User field and forcing it to be unique and is required I'm not sure there is a stock way to do it, no.