Keep in mind I was referring to the version here when I mentioned "Southern Peninsula."
The Itch and Steam demos have a different, smaller map.
That being said, I must apologize.  I misremembered the map thinking the peninsula was to the south-east when it's actually to the north-west.  i don't how my dumb ass head thought that without realizing it.
Here's the map of where you need to go, Serpents Perch:
	
		
			
		
		
	
View attachment 4472162
	
		
			
		
		
	
A word of warning, the dragon-riding mount portion of the code is bugged is bugged as hell, usually with game-braking issues (dragon mount starts flying backwards and no longer gains altitude; can't dismount the dragon normally, and when you somehow do dismount, it's impossible to interact with anything unless you respawn yourself).  So I wouldn't recommend completing the dragon's quest unless you saved before hand.