Looks like the tank is mounted crooked in the triangle. Notice the difference in the gaps between front of tank and frame tube vs. rear.
(pic #2)That would affect tank fitment and cause possible problem IMO.
I just looked at my k5 and the tool tray is very close, but doesn't touch the vent fitting/hose. Not sure what's causing your tank alignment situation. I'm no expert, so I won't go so far as to say a bent frame....Anyone?.......or like Henning mentioned, maybe wrong oil tank. I could be way off, just throwin it out there..