I followed all the flour/water proportions in this recipe, but after the 12-hour rise the dough was so sticky and wet that I couldn’t shape it without adding more than a cup of extra (white) flour to avoid sticking to my hands and the board. The original flour mixture I used was half rye and half mixture of whole wheat and white - plus my own sourdough starter. Final result was excellent taste and texture and good rise and crust - except I had to use a slightly lower temp in my digital oven (460) to avoid burning the bottom. So I figured out the temp - but what about the VERY sticky dough?
This dough is indeed very sticky because of the large amount of rye flour, the sticky molasses, and the water. The best ingredient to reduce if you’d like the dough to be more manageable is probably the water. Start by holding back 60g water or 1/4 cup.
Sometimes stickiness comes from the dough being overproofed. If your kitchen is warm, you should shorten the bulk fermentation. Make sure the dough isn’t expanding too much. You can also mix the dough with cold water to slow the bulk fermentation down.
Here are some tips for handling this dough that I wrote up a while back that you may find helpful.
As for the burnt bottom of loaves, the lower oven temp that you did is a great way to fix that. Another option is putting a baking sheet directly under your dutch oven/baking vessel about halfway into the bake (same shelf, with contact).