@zorxique I’m not much of a fountain pen user myself, but my understanding is that Field Notes paper is inconsistent: the paper in their standard notebooks (flagship Kraft notebooks, as well as Chicago & PDX, etc) is usually only about 50 or 60#T, and therefore might show considerable bleed-through. And the grain might cause just a bit too much feathering for your taste.
But some of their special editions have thicker, smoother paper that might be better for fountain inks. For example, End Paper, Front Page — as well as the Signature and Autumn Trilogy that you bought — all have similar weight papers (70#T) that you may find much more fountain-friendly.
Hope this helps!