Michael,
It sounds like you are describing what is called a "compensation hook."
That is, it it located somewhere between a nose hook and a CG hook.
It is better for ground launching than a nose hook is but not as good
as a CG hook. Likewise, it is better for aerotowing than a CG hook but
not as good as a nose hook.

I am really surprised that no one answered you sooner.

Raul

wrote:
When the aircraft manf has not done the research or made any
recommendations - how is the location for a CG hook computed?

One example - the SGS 2-33 installations I have seen (not factory) seem
to be far ahead of the actual CG.

TNX

Michael