Just because it's a Piper, doesn't mean the guages are accurate.
With experience, you can learn to "eyeball" the tank levels using the sidewall, but dipping with a highly sophisticated, calibrated measuring device (a bit of wood with marks on it....) is far more accurate.
The dihedral does make it a bit more complex than a 'flat' wing, the only problem we've had is getting hold of a properly calibrated stick.
The a/c fuel logs should also be an aid for working out how much you have onboard, but as long as you have no weight and balance or performance issues, then fill it up before flight.
As has been said before, the only time you have too much fuel is when you're on fire!