I use a take a look mirror on my helmet (
https://www.mec.ca/en/product/5013-6...ist%27s-Mirror). I know you said you didn't want a helmet mirror but maybe you need to give it more time. I love that I can see forward and back at the same time and I can swivel to scan behind me. I have gotten so used to this I find it hard to ride without it. I have never had issues with it being small.