I forgot to ask, how much population fits into a cargo space? Hopefully its not 1:1 because 50 freighters loading 5000, or actually even 7250 pop per trip with skills would take over 1,100 trips to remove 400mu pop and the pop would grow faster than it could be removed.
*forgot to mention in my previous post that cargo ships would be 3x more efficient resource wise then freighters but 150 cargoships instead of 50 freighters hurts the object cap a bit.