At the point when you have to convert between string types and can no longer easily use much of libc without conversions, why not just use a different language that's already gone much farther in the name of safety, usability or other features?

In other words, if your pseudo-c candidate already suffers from most the interop problems that Rust, D, Nim and Go do, why not just use one of those and at least reap the other benefits they provide?