Great puzzle! Found it easiest to solve in Inkscape, where I could copy-paste things around, and easily remove old bits if I realized I'd made a mistake.
I think the most confusing part of the puzzle is that (rot13) gur gjb xvaqf bs pyhrf ner shaqnzragnyyl qvssrerag. Gur "k" pyhrf zrna gung lbh pnaabg qb *nal* bs gur guerr guvatf gurl fubj (tb qvntbany, pebff gur bgure pbybe, naq punatr onpxtebhaq pbybe) rkprcg sbe jurer lbh qb nyy guerr. Ohg gur "obk" pyhrf nera'g nf erfgevpgvir -- sbe rknzcyr, gur gbc evtug pyhr qbrfa'g zrna gung gur benatr yvar pnaabg ghea jvgubhg cnffvat guebhtu na benatr obk ba n yvtug onpxtebhaq. Va rssrpg, gur "k" pyhrf vzcyl gurve pbagencbfvgvir (vs abg punatvat onpxtebhaq pbybe, gura pnaabg pebff bgure yvar), juvyr gur "obk" pyhrf qb abg vzcyl gurve pbagencbfvgvir (vs abg cnffvat guebhtu obk, gura pnaabg ghea).