I tried a simple mechanism for the tipping. It is basically a geared motor with a small winch pulling a lever, which does the tipping. This is the first try and I managed to lift it with a 11 lbs load. Not bad. Now I can optimize the design and I am considering putting the motor in a different spot. the space behind the cab is perfect for the battery.
Here a video:
https://youtu.be/CMy56WsefUk
Kerst