With front mounting you obviously will have longer plumbing because you do not go directly rearwards but forward where the exhaust will not be allowed to exit.
Depending of the position you will heat up the other components that are mounted in the vicinity. I think you rather heat up the gearbox and the dampers than the fuel bladder and the ES batteries.
But ultimately with the current rules all that matters is aero efficient packaging. If one position allows better airflow over the rear end that will probably settle the issue.