Chinese-ish writing: How far can zhi extend?

I'm noodling with a zhi-like writing system for kimwa lilyeho
(http://www.talideon.com/concultures/wiki/?doc=kimwa%20lilyeho) and
eventually for kimma (http://www.talideon.com/concultures/wiki/?doc=kimma).

I've come across the imstrumental and ablative constructions, which both use
a simultaneous prefix and suffix. So, using |chih| "east",

Inst: kuwochihka
Abl: honjihka

Would be okay to use the zhi construction [INST]-[east] to stand for
kuwo-chih-ka? It would be assumed one had to add the suffix if the case is
just indicated, yes?

Well, *I* think it's a nifty idea. :)

Ben