> Offhand I don't know if Wikipedia has a policy on references to Internet Archive / wayback-machine links to things

They do have a policy.[1] Additionally, IA has been specifically crawling links on Wikipedia to preserve the citations.[2][3]

1: https://en.wikipedia.org/wiki/Help:Using_the_Wayback_Machine

2: https://blog.archive.org/2013/10/25/fixing-broken-links/

3: https://archive.org/details/NO404-WKP/v2