Probably the laziest suggestion possible, but make it so that you can store a certain amount of a single bone type with Robin after Morytania Elite and he’ll automatically convert them to bonemeal/slime of that type and deposit them into your bank daily, similar to buckets of sand in Yanille. I only say make it Morytania Elite reward to justify the convenience and ease of it and it doesn’t trivialize it because you had to earn it.
#Store bones at Robin
sturdy vale
Could also make it an earlier reward and just make the amount stored increase. The limited amount is also so that you still have to get on and put more in so you can’t just store X bones and be gone for like a year and come back to it.