The last posts about filler cap positions and dipsticks on low stable wings is absolutely right. The same goes for my Cessna 303. At airfields with low security, there have been fuel theft issues through the drains, and even my Shadin FF totalisers will not help in that case.
I was told that there was a mod for Beech turboprops that allowed sight guages in the underside of the wings where you could visually check fuel at different points of the wing.
Does anyone know if this is possible for piston engine A/C ?