2000g sourdough boule in medium sized dutch oven I've been just starting to get into baking. I made my own starter and I've been following the tartine bread recipe to reasonable success. The problem I continually run into, though, is weak oven spring. I understand that there are a bunch of factors that are difficult to isolate that go into this. Despite my loaves pancaking, I'm usually able to get a pretty nice hole-y crumb, which leads me to believe that the difference between the loaf size and my dutch oven could be a major culprit (it's maybe 2 inches in diameter larger than my desired loaf). 

So, I wonder, what if instead of separating my dough into 2 loaves, I just bake it all at once? Is there anything I should know before trying this?

Here's my recipe:

Leaven:
1 tbsp starter
200g 50/50 bread flour
200g water

Dough (2 variations):

Rye:
200g leaven
180g rye flour
710g all purpose
800g water
20g salt

Whole wheat:
200g leaven
700g whole wheat flour
300g all purpose
750g water
20g salt

Steps:
1. Mix leaven, let rise for 10-14 hours
2. Mix dough ingredients except salt and 50g water, autolyse for 30 mins.
3. Add the salt and remaining water. Bulk Fermentation for 3-4 hours, turns every 30 minutes
4. Separate into loaves, light preshape to create surface tension, bench rest for 30 minutes
5. Fold each loaf once, shape into boule. Final rise in shaping bowls 2-4 hours
6. Bake in dutch oven at 450 F, lid on for the first 20 mins.

Thank you!!
Weak ovens still get to needed temperature, but slower and/or they may "leak" heat. The only way around it is to "accumulate" heat by placing baking stone into the oven, and (Thanks to Alton Brown creativity) place upside–down large clay pot around the bread. Naturally, you need to pre–heat them before you place the dough in.

Stone and clay keep heat much better then steel your oven is made of. Also, they distribute it more evenly.

This technique is similar to baking in a dutch oven.