I'm a professional private cook in Rio de Janeiro. I also teach here. Fresh bread is a major part of my teaching regimen and I have successfully taught my students several different types of breads, everything from focaccia to Italian bread for bread bowl soups.   I recently had an opportunity to do some baguettes for a friend's French cafe and I've been working on the system. I use an 80% hydration recipe that involves many stretch and fold sessions with 45 minutes in between. Though I follow the instructions, I'm having issues with the dough being so wet at the end that it's impossible to shape correctly. It's so loose and visibly wet that it practically runs off the pan.   When I form the baguettes in the couche, they puff up a bit, but when I remove them and attempt to transfer to my baking stone, they just turn into flat bread and don't recover. The taste is great, but you can see from the slashes from the lame, that something isn't right. Plenty of bubbles and when I'm working it, it expands quite a bit during rest periods. But it's just too slack.     I'm using a typical type 1 bread flour. Here in Rio the weather is cool and humidity is very low right now. What is causing this? 
you will change the flavor, you know, since anything you add will alter the recipe - even things with very neutral flavors will dilute other tastes.  I'm guessing you want to not alter it much, encourage a similar flavor profile, or add things more neutral in flavor.  A few simple options - you can up the egg content (two eggs instead of one), as eggs have a high percent protein and there's one already in the recipe, so the flavor shouldn't change much (this might give you a bit firmer texture, your call on if that's a plus or not).  You could lower the amount of potato (or up the amount of cod), so the percent of cod is higher in each ball.  You could make a protein-rich sauce to pour on top (depending on what sauce or seasoning you usually use with it).  Alternately - you might try adding some protein powder (most of the ones I see are sweetened, so be careful).  You might look for TVP or TSP (textured vegetable or soy protein) - which is very neutral in flavor and also quite inexpensive.  I would recommend crushing to a powder before re-hydrating - this can be done with mortar and pestle, blender, or grinder, whatever you have - or blending afterward to minimize the texture change if you don't like it.  You might add the tvp paste to the mix outright or substitute some reconstituted tvp paste (mixed with water or milk) for part of the mashed potato for a higher ratio of protein to carb. 