I had a less severe case of supervisors who are not experts on stats. I took an advanced stat course to refresh my knowledge on that topic. The key is to then look for papers with similar research problems and inspect their methodology. In my case I even found the 'holy grail': a set of methodology papers for my domain. When a peer reviewer has any stats remarks on my paper now, I find it's because he's not expert on stats and I can simply quote from and refer to state-of-the-art methodology papers. I really believe every research group should have a tailored 'methodology package' it gives to all who join it.