You can wrap it around the base of the tree and move it up as you climb (sort of like one-sticking), or you can climb up with a linemen’s belt and hang it at height. Both are no less safe than climbing with a saddle, Mr. Smarty Britches.
Kind of my point though! Climbing trees is dangerous. Sitting on your butt hanging from strong stuff, or sitting on stuff while hooked up to strong stuff, is still dangerous, but much less so.
The more we separate climbing from the rest of a hunt in thought, conversation, and in gear, the safer we’ll be. That conflation is going to kill someone.