Heres how I would start to go about it: I would buy a small inverter 12Vdc to 24Vdc (about $10). One will likely need to tie both 24V and 12V commons of the inverter together, if the sender or display electrics are connected to the vehicle body (12V common), and highly likely they will be. First however, one would check with the inverter manufacturer to check if it is ok to connect the commons together on their inverter. If however the display and sender bodies are not connected to the common (vehicle earth) i.e. are fully isolated (floating) from the 12V common of the vehice, then one would not need to connect the inverter commons together. I have this in my vehicle, but the opposite way around. I have a 24V inverter to power 12V to my bank of USB sockets which are fully floating.