My preference is to hunt on the ground so I can stay mobile and follow elk from a distance. When conditions are right (wind, thermals, cows, etc) I make a move. It was nearly impossible to pattern bulls this year...one day they would be in one draw and in another draw the next. I've often found that it is often tough patterning bulls to a specific draw, bedding area, etc.
The wind often constantly swirls and changes directions during the day. I'm not sure if that would be a very good scenerio...especially in a tree? I've noticed several years where wallows were used super early...possibly only used as early as when bulls first shed their velvet. I've also noticed that wallows were used very little closer to and during the rut. It may be possible from a tree if there is limited water (for both drinking and possibly wallowing) or a particular draw, patch of trees where bulls wander and bed.