The essential idea here is that of the nearly 500,000 hospice volunteers in the US, there are likely many thousands of them who work with dementia patients and have learned how to support these patients through their own trial and error.
Taken together, these volunteers represent a vast trove of experience and wisdom. Unlike the primary caregivers for dementia patients, hospice volunteers choose to provide this support, and therefore might be more pre-disposed to sharing what they've learned with others.
This idea could be realized by working through a national hospice organization, like NHPCO.org, and/or via establishing partnerships with various individual hospice organizations across the US.
Initially some research would be needed to identify alternatives for identifying hospice volunteers who have the requisite experience; and then figuring out what the best channel would be for helping caregivers connect with them. This could be anything from a video-enabled mobile app to a web forum to local support groups.