> 2. Add libraries to the sample implementation for at least bytevectors and flexvectors.  It should be very little additional work to add them for the twelve SRFI 160 homogeneous array subtypes; I don't think they make much sense for strings, bitvectors, etc.  This should also be doable silently; it's basically 14 tiny .sld files.
>
> 3. Add a PFN to SRFI 223 saying that the sample implementation provides these libraries.

No problem, as long as they’re in sublibraries.