Savage Wombat
Hero
For the sandbox-ish game I'm designing, most of the hazards are contained in mini-dungeons, not wandering the countryside.  So my means of avoiding the problem under discussion is this: each dungeon has a "threshold monster" at the entrance.  This particular monster is of a CR that defines the dungeon's threat level, and is not interested in pursuing the PCs should they choose to withdraw.  (As I write this it occurs to me that it also should have no treasure.)
Thus the dungeons have a "you must be this tall to ride" sign out front - if you try to enter the Turathi Strategic Necromancy Reserve and can't handle the first monster without taking a beating, you might want to wait a level.
				
			Thus the dungeons have a "you must be this tall to ride" sign out front - if you try to enter the Turathi Strategic Necromancy Reserve and can't handle the first monster without taking a beating, you might want to wait a level.