Long distance boating with limited fuel means you need to have accurate fuel management. For our first launch, we installed a Standard Horizon FF41 fuel flow meter (no longer imported). It was the same as the Navman Marine F41 from New Zealand, which was one of the first digital fuel flow meters.
Most modern outboard engines now come with fuel management as part of their electronic instrumentation package. Usually an option, but now more and more becoming a standard feature.