That's a valid use case. For opt-in per link, you can disable global link interception with `mu.init({ processLinks: false })` and then add `mu-url` explicitly to the links you want µJS to handle. For the variable base path scenario, the `urlPrefix` option in `mu.init()` might also help. It prepends a prefix to all fetched URLs.
That said, proper support for relative paths is on the roadmap.
If I were to adopt µJS, though, I would probably want to opt in on a per-link basis.