There’s no build in way to do this, but if your comfortable with code, then I can point you in the right direction how to do this. But it will involve changing the SQL query a bit.
@tijmensmit – going code
would be GREAT! Comfortable enough yes, and it would really save the project.
@tijmensmit – if you would like to PM me the necessary code/location, just let me know.
Sorry for not getting back to you before, clearly overlooked this one.
I misunderstood your initial question, the code I have will regardless of the set radius return 5 ( or whatever ) rows, not less or more. This is part of the next update where if no results are found it will show a text asking the user if they want to see the x nearest locations regardless of the search radius.
If that works as well for you, then I can explain how to make it work that way with the wpsl_sql filter.
A search on Stack overflow showed me this thread with HAVING COUNT to set a minimum value.
I didn’t test it, but HAVING COUNT( posts.ID ) > 5 should do it in combination with the wpsl_sql filter. Here is the existing SQL query that you can overwrite with the filter.