OB1
Jedi Master
Just had a thought about the spending Hit Die to recover HP on a long rest. Why not ALSO require spending HD to recover spell slots on a rest. You get back a number of slots equal to what you rolled on the die (ie a 2 would give you back 1 2nd or 2 1sts). Now a long journey away from a safe place to rest get's REALLY challenging. And then, instead of exhaustion for failed death saves, lose HD instead (maybe exhaustion if you don't have any remaining HD).