Query filter on Polymorphic model?

Hi all,

I'm trying to paginate polymorphic Contacts (Business or Person).
The problem is, I can't find a way to add a query filter on the Person model.
I want to get all Contacts, be it a Business or Person, but a Person CANNOT belong to a Business. (for this result set)

My goal is to have an overview of all Contacts, and paginate them.
But I need to exclude the People that belong to a Business.
So, in short: How do I put a filter on my Person model, through the polymorphic Contact model?

I could just fetch 100 Contacts, and use a collection filter to exclude the People that I don't need.
That works. But the query still fetches those unwanted People.
Plus, I can't work properly with pagination, because I won't have 100 results anymore, but maybe 60.
If I would do that, I have no estimate of how many results I would get, and therefor can't paginate them.

I would like to do something like this:

Contacts::filter('people.business_id', '=', null)
    ->orderBy('created_at', 'DESC')
    ->skip(0)->take(100)
    ->get();

And get the following:

1  |  Business X
2  |  Business Y
4  |  Jane Doe      (business_id = null)

Tables:

Contacts
--------------------------------------------------
 id   |   contactable_id   |   contactable_type
--------------------------------------------------
  1   |                1   |   App\Business
  2   |                2   |   App\Business
  3   |                1   |   App\Person
  4   |                2   |   App\Person


Businesses
----------------------
 id   |   name   
----------------------
  1   |   Business X
  2   |   Business Y


People
---------------------------------------------------------
 id   |   business_id   |   first_name   |   last_name   
---------------------------------------------------------
  1   |             1   |   John         |   Doe
  2   |          NULL   |   Jane         |   Doe

Happy holidays to all of you!