I always dreaded fillin the scamps water tank as someone would have to lift the cushions and the wooden hatch under the seat to see how close we were to being full (or empty for that matter) and filling by yourself was worse. I bought a marine inspection port and cut a hole on the outside of the scamp
after carefully measuring where the best viewing location would be. That area of the camper is flat too by the way. Now I just unscrew the cap and check the level right there where I am filling it!