(Ingenuity aside...) Why use a bearing when nylon has been proven by many teams to be just as effective? Even a brass bushing would be less expensive and probably lighter than a bearing. The efficiency loss between the two is somewhat nominal; this year's FTC shooters are a good example.
My current favorite chain tensioner sprocket:
https://sdp-si.com/eStore/PartDetail...&GroupID=58 5 (ignore the pictures, look at the material type)