The Option to get the fuel density at so said airport and apply it to generating the release. Im assuming that it wouldnt be a hard addition feature considering the APIs available for fuel density anyways.
also an option for the airframe to set it to planes default. some aircraft developers have their fuel denisty at 6.75 instead of 6.70 throwing off the default numbers by +/-25 lbs even though not a big issue but it can be down the road at a heavier weighted aircraft taking off from a shorter runway