The reason fuel lines get brought up is our trucks use a fuel pressure regulator that flows the excess fuel back to the tank, and during its trip up to the engine compartment and through the rails the fuel gets quite hot. This thermal energy is just dumped back into the tank increasing the temp of the fuel beyond ambient.. or ambient plus all the heat under the rig.
If the fuel were cooled before getting back to the tank this would eliminate a major btu source.
This is a lesson the OEMs know well, and have made design decisions around, even if for different reasons than we are discussing. Some vehicles (the 2008 Escalade my L92 came from comes to mind) use a returnless fuel system partly to simplify plumbing and safety but primarily to reduce heat return to the tank which drastically reduces evaporative emissions.
Ah - that makes sense. Thanks for the education