Underproofed?

I have made sourdough a few times now. My starter is about 6 weeks old. Seems pretty healthy as it triples in size after a 1-4-4 feeding of 70% bread flour/30% WW flour.

I feed my starter before going to bed.

Start in the morning with 60 Minute autolyse prior to adding starter and salt

5 1/2 - 6 hr bulk ferment (including stretch and folds) at 80* (oven with light on)

Pre Shape and then final shape before putting in proofing basket

Usually about a 2 hour proof before going into the dutch oven. Poke test still leaves a little dent (85-90% recovery)

Here is what it looks like coming out of the oven

Here is first look at interior

And deeper into the loaf, I find some extreme tunneling.

From what I see, it looks like a "fake crumb" from underfermenting.  

I have time to let it bulk ferment or proof longer.  I am usually done with baking by 5-6pm so I could add an hour or two to the process.  I like to do it all in one day if possible, but I could cold retard it in the fridge overnight and bake the next morning.

I don't have an experienced sourdough baker to get first hand information, so I have to diagnose online. Looking to you for any guidance you can provide. Thanks in advance for any tips or suggestions.

Bill in Idaho