Ok everybody, mark this on your calendar, Ken's gonna admit to making a mistake!!! [X(] [X(]

I've done the same thing and here's what I do to keep my orientation when working on a plane and I have to pull the fuel tank in and out. I use a sharpie and mark an "up arrow" on the former that I will be sliding the tank into (or inside the tank compartment, or whereever I can see it and it will help) and an "up arrow" on the sides of the tank. This way as I slide the tank in and I see that the arrows don't "match" I know it's upside down.

Hope this helps

Ken