EDIT: Made a more compact version 2 with the help of JK here. This one requires 52 fractionators per belt but has smaller footprint and fewer belts required.
Saw a couple different pile sorter fractionator blueprints and it got this idea in my head. This is the smallest footprint tileable fractionator blueprint I could come up with. Drag 25 tiles out for 50 total fractionators for a full 4 stack belt in and out.
Limitation: You must drag to the right as it might not work if you drag to the left. You must also close the loop of hydrogen manually on both ends.