A quick amazon search brought this uphttps://www.amazon.com/eCostConnection-Extreme-Waterproof-Adjustable-Microfiber/dp/B06WP28NP1/ref=sr_1_22?crid=1J0BMJJOZCNP0&keywords=chest+harness+cell+phone&qid=1557711023&s=gateway&sprefix=chest+harness+cell%2Caps%2C130&sr=8-22
This looks to me like your best chance from the ones I saw of the park oking it but that is a guess on my part. remember you have to get it oked each visit by a supervisor at guest services and carry the approval card with you at each ride. Also the ride ops at the rides have final say they can veto it they have concerns but I never have had them look at anything but the approval card. Hope that helps.