If the cost of individual insurance is prohibitive for your practice, it may be possible to reduce any risk exposure by considering/utilising the following:
At the initial meeting with a potential directee, develop together an agreement setting out what each expects of the other, and include a statement which clearly states the nature of the companioning process, and what it is not. The responsibility for drafting such a document rests with the individual director, although many experienced directors already utilise them and could perhaps share what they have. You might also wish to approach a legal practitioner to help in the drafting.
If you haven’t done so already, you might like to explore the possibility of offering spiritual direction under the umbrella of an organisation which could provide P/I cover under their policy. You may be asked to pay a fee. You may also be asked to provide annual information regarding ongoing formation, professional development etc.