HMMM
I've noticed that some (I've seen a few) experimentals don't comply with the regs as to where markings should be placed.
Part 45 says, in part:
(a) The operator of a fixed-wing aircraft shall display the required marks on either the vertical tail surfaces or the sides of the fuselage...
(2) If displayed on the fuselage surfaces, horizontally on both sides of the fuselage between the trailing edge of the wing and the leading edge of the horizontal stabilizer...
Then again, I have never heard of anyone being violated for this, either.