Sounds like you know what you do & don't want. Fair enough.It is more than a little easier to gain access to RAM (example: zero day expoits) than to gain physical access, which is a significant disadvantage of dm-crypt etc. vs. device managed keys
I think WD has developed a technology to solve this problem:Not an answer to your question, but I recommend to never use any drive-based encryption. Too easy to lose keys or lock yourself out and lose all data.