Below some solutions, experiences, etc that may be useful for others. Comments welcome!

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Fuel volume/gauge measurement

Pump out fuel via the engine fuel hose connection. Fill up in order to see how real volume corresponds to the gauge. Tank capacity 250 liters according to Xc 42 specification. Max 200 liters can be used in reality...

Jib inhaulers

By adding inhaulers the jib can be trimmed for better upwind performance and sailing closer to the wind. This solution should be possible to implement on most other boats so welcome to copy!
Photos of v1.0 below. Still some ideas for improvements...