tl;dr: cancel your big deals and transitional agreements (they're not working) and invest in a set of hundreds of non-APC, OA titles offered by Open Journals Collective, which derives from the OLH model. Email Caroline Edwards (at Birkbeck or at OJC) to get involved.
Martin Paul Eve (Wed,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: