As the main campaigner to get the graphic novel "Watchmen" declared elgible for Best Novel Hugo in 1988, i think you can anticipate that i'm going to disagree with you.

And where i disagree is your definitions -- possibly implicit and unconsidered definitions on your part -- which lead you to the conclusion that SF is a thing apart from fantasy.

It ain't, you know.

In fact, Science Fiction is a subset of Fantasy.

Therefore, no matter what rules you may make, a fantasy novel always has and always will win the Hugo -- the only distinction being that sometimes it'll be swords-n-sorcery and sometimes it'll be computers-n-blasters.

Much of Andre Norton's core output was easily and eagerly accepted as "SF", but is really fantasy with a thin "SF" gloss. Where do you put it?

My own brother David's "Path of the Fury" is a pure space-opera adventure, with savage pirate raids on weak worlds, powered battle armour and oddball stardrives and enhanced human beings and a fully aware AI controlling what is essentially a PT boat with the sheer power of a battlecruiser... And Tisiphone, a demiurge, one of the Greek Furies, as a major character.

Where would you put that one?