Sec. 20. Agreements may be made among insurers with respect to the equitable apportionment among them of:
(1) automobile;
(2) bodily injury liability; and
(3) property damage;
insurance which may be afforded applicants who are in good faith entitled to but who are unable to procure such insurance through ordinary methods. The insurers may agree among themselves on the use of reasonable rate modifications for the insurance, and the agreements and rate modifications are subject to the terms of this chapter.