If you have access to nutrition software, I would suggest a multi-recipe process. I used Esha Genesis, which is my preference. It you are doing manual, I'm sorry!
My first question is whether or not the pickling brine and the jar brine are going to be the same. If it's the same, you can take the average cucumber weight (unbrined) and net weight of jar contents to figure the difference of the total brine. Some might prefer to create a single recipe with these weights and adding all other ingredients.
For absorption, you can pull some before brine/after brine, cucumber weights to get the average increase and go off that.
For the nutrition calculation I personally prefer to handle this as a multi-recipe product. Others may prefer one recipe with all ingredients, I favor multi-recipes that make it easier in the future. I will say that I tend to over think things 
- Recipe #1 - I would first build the pickling brine recipe and save. This is helpful if you would use the same pickling brine for other pickled products.
- Recipe #2 - Create another recipe that for the brined pickle. It would consist of the weight of the cucumber and the pickling brine (recipe 1) average absorption weight. This would give your nutrition info on the brined pickle (without jar brine).
- Recipe #3 - This recipe that would be for the finished jar. It would consist of recipe #2 (brined pickle) weight, and recipe #1 (brine). This would give your jar nutrition that you would break down per your serving size/RACC. This version takes into account the jar brine as its part of the finished product. There may be more absorption, migration and some people consume the brine. Also, if you happen to use a different brine for pickling then what is used in the finished jar, you would create a recipe and use that in your finished jar recipe instead.
Others may have a different process, this is how I would tackle it. My process has multiple recipes as I have worked in a facility that used the same base recipes for several different finished products. So it helps to be able to pull in a base recipe instead of recreating it every time. For instance, Recipe #2 can easily be added to different recipes, where maybe the jar would be larger and have more jar brine percentage than a smaller jar. Or you can use Recipe #1 as a base and add sliced pickles, so on. Saves time in the long run.
Hopefully i've described my, convoluted thought process in a way that it makes sense. 