A problem with shooting a bedded elk is the position of the 'elbow' on the front leg. It partially covers the heart & lungs. A light bullet might have a problem penetrating. Also, the lower half of the chest is where the vitals are and a bedded elk presents the top half.
I haven't had a need to try it to see if it works but I think I would get ready for a standing shot then whistle softly until it got curious enough to stand up.
