In MUDSEASON 2020, available in Members Only Resources, you will find my article about owners voting to permit non-owner membership in our Statutory Association using a form of proxy voting. I invite you to read it. Our proposed amendment, its wording and intent, was approved by an Attorney.
Although "membership" and not "proxy voting" was the outcome for approved non-owners, I believe your owners could amend your By-laws, or vote by majority, to permit the definition of proxy voting to include non-owners.