Actually I think I figured it out. Read this guide.
Not sure if this is relevant, but I ran the hackintool again and it was still showing as 655 mobile, so I changed the platform ID to match the one in your screenshot and it now shows as a 630. Again, I'm not sure if I had just done it wrong last time, but I also notice that there are other platform IDs present in the dropdown box, these look like different SMBIOS that I'd tried previously, do you think something is left behind when trying these? Might that explain the odd behaviour? Thanks!
I've got a similar built that I just put together, but with a i5-8400 and a RTX2080 (planning to use iGPU with macOS). Even without the GPU installed (I know that's going to be a whole other thing later on) The system reboots when I try to format the APFS volume while in disk utility, or randomly at other points in the recovery partition like choosing "install macOS". I've copied your EFI folder to the USB disk and matched the BIOS settings exactly. Admittedly I'm new to this, but hopefully it's some simple boot arg or BIOS setting that I'm missing. Thanks so much for writing this guide, any suggestions you might have are much appreciated!
EDIT: Also made sure I updated the BIOS, since it was still on a September build.