Yep, I only use my gas tank on my snowbike, hate it on other bikes for the same reason of hitting knees.
I use a super slim X-Lab Stealth Pocket 100 in place of the gastank for my fargo and lynskey. Perfect racer size for my stuff. But I also run a bottle cage on my top tube, along with a jerrycan or other toptube bag on top for the extra storage (mainly camera)