AndyMan Great question, Carrot Fiber holds up to 26 times its weight in water, and while the 80 oz is still well inside that I have never done that before. I max out (even with Carrot Fiber) at 64 oz which is 2 qts. My only fear with doing 80 is that it might take a lot longer to cook as it will have more water content that will be trying to evaporate. Most of that water should be bound up in the carrot fiber though so it wouldn’t really be available to be cooked out. Hmmm, my recommendation, to be safe is to stick with 64 oz of water.
Now, as to should you add more seasoning, some people will taste the difference if you did not add additional seasonings and some (most) will not. Your water and your seasoning is technically part of your meat block (anyone who is reading this who doesn’t consider this don’t worry!) so adjusting your meat block to include your water is sometimes done. If you do decide to add more spices or seasonings I would add aromatics and things like Rosemary and Basil, don’t add more salt as that is formulated specifically for the meat block.
Hope this helps and if you do decide to go with 80 oz of water then I would be very interested in the results!