How do I adjust a bread recipe for long, cool proofing?
Seeing the recipe now, my only advice is: don't. 

Long proofing is something which is done with white wheat bread to add some aroma. And it depends on the yeast having very good growing conditions. 

What you have here is a quite complicated dough. It has a ton of pumpkin in it, and most of the flour is whole wheat. And then you are adding spices, which have yeast retardant properties of their own. This is a dough which will have trouble rising. Keeping it alive for 24 hours won't be too easy, getting a decent rise out of it will be worse, and getting good added taste instead of some off tastes with this mixture is in the stars. 

And even if you managed to proof the dough well in a long process, you won't get the effect you are hoping for. In pure wheat, a long fermentation gives you subtle fermentation aromas, but nowhere as strong as sourdough, and a very specific texture which people tend to seek out. You can forget the texture in this overloaded dough, and the spices will cover the taste change pretty much. 

Just use the recipe as intended, and if you want long-fermented bread, take a recipe which is meant for that, there are enough of those around.