I have been following that situation. I've been messing with those adapters for a quite time, and I conclude that the whole problem is due to some interference that comes from G1-Bus which affects the SATA adaptor.
The most effective solution would be make a PCB design in order to avoid all that wiring, which is the cause of those problems. Yes I know that some kinds of SATA adapters do work as expected and other do not, but the main problem are not the adapters but the wiring itself. No matter how "good" is the wiring, there will be always a problem of stability.
The problem get even worst when we have to use an non-GDROM bios (without the GDROM board), because those adapters do not work well if no MASTER device is present. If we had a bootloader that could work in MASTER mode instead of SLAVE, then at least one part of the problem would be solved.
I hope that @Megavolt still have plans to release a bootloader bios with such feature, because in that way we could use an IDE-to-SD Card converter like this one:
https://www.ebay.com/itm/New-Secure-Digi...0887386367 (the problem with this adapter is it only works in MASTER mode)
Then would be perfect, cost-effective and practical.