IDEAR 2PCs Chin Straps for Users, Anti Snoring Chin Strap to Reduce Air Loss, Breathable and Comfortable for Men & Women

You may want to try this one found on Amazon. https://www.amazon.com/dp/B0D83396LN?ref=ppx_yo2ov_dt_b_fed_asin_title It's a single strap with a large chin cup. Adjustment is only on one side but it might give you enough adjustment.