Further to my last message I would recommend adding the CPUFriend kext otherwise the CPU will have a minimum clock of 1.2 GHz causing unnecessary battery loss.
For reference Windows will step down to ~0.5 GHz at idle.
Here is an easy one key CPUFriend configurator. Run this and set your minimum clock 500Mhz then copy the files to your EFI Clover folder. I’ve also disabled CFG Lock on my BIOS but I’m not sure if that’s required.
Either way this yields similar battery life to Windows now at around 5 hours for regular usage.
On another note I’ve discovered 4K output via USB-C and Mini HDMI is broken on all available configurations. I’ve tried a few well known fixes (stolenmem increase, custom resolutions via EDID override, activate monitor on wake) but haven’t managed to crack this yet. Will post back here if I discover anything.