Cessna Wing Skins

My Cessna 172 M (1973) is being annualed. The top wing skin panels above the
wing tanks (Standard tanks) have to come off to inspect the area for
corrosion. We got all the screws removed. According to the service manual,
that is all that is supposed to be securing the panel. (Dozens of screws
around the perimeter of the skin and six screws around the fuel filler neck
is all that is stated to be removed). The skins would not remove after
careful tugging and pulling. (the fuel cap was removed for this).Then I
finally found three rivit type fasteners also around the filler neck. They
apparently hold the skin in place in addition to the six screws but there is
not any reference in the manual about removing them or drilling the heads of
the rivits off. If they are indeed rivits, they are flush head type because
they are smooth with the skin's surface. The heads are about 1/8th inch in
diameter. I was hoping they could be merely some alignment pins. I removed
the small inspection cover over the fuel transmitter (sender) to get a
better grip on the panel near the filler neck. When trying to gently lift
the skin panel upward, it is obvious that the three rivits are attached to
the panel and to a flange underneath the panel that apparently secures the
filler neck. The panel would not pop clear of them. So I don't think they
are alignment pins.
Anyone familiar with this to advise drilling these three fasterners to free
the panel?
Thanks,
Tom Cummings