I think it would serve well to wilderness activity to have the level 40 chaos altar near the ice plateau oblesik to have the abilities to:
A: Grant the same amount of experience as a gilded altar when bones are used on it
B: Have a 50% chance of not consuming the bone, while granting full experience
Along with this, have an npc placed next to the altar which has the ability to unnote solely bones.
I believe the danger of the wilderness would balance the bonus well, and would not devalue normal gilded altars due to the lack of risk associated with them.