Hello. Maybe can be useful for you look for the work “proxy” in the forum. You can read about people using what you suggest before.
Ah! and read this: Proxy files - different approach from my workflow with GoPro footage and this Keyframes & Proxy Editing if you plan to use proxy files
I’m experimenting with this too, lowering video quality (using h.264 very fast preset in handbrake, with a quality adjust of RF 29-32) for editing, and substituting files with the full quality ones for export.
Please, tell me about your results.