In the latest vector proposal (draft of version 1.0), there is the following restriction on widening instructions (section 11.2)

For all widening instructions, the destination EEW and EMUL values must be a supported configuration, otherwise an illegal instruction exception is raised.

This seems unduly restrictive and will limit software portability.  If the destination EEW is supported but EMUL is not, it would improve code portability if strip-mining reduces VL accordingly instead of raising an exception.

Similarly,  code would be more portable, if any proposed combination of SEW/LMUL is replaced by SEW/LMUL2 if SEW is supported and LMUL is not.  LMUL2 would be the highest supported group multiplier for the given SEW.