What about a big electric motor at back , and connected with wires at front to move electricity
If you size this motor, you will find the problem. Have to take into account where you want to place the heaviest stuff found on ship in the free body moment diagram.
You can get away with it somewhat more on a submarine, as the whole thing submerges and you can size/place the ballast tanks to compensate (somewhat) if there is benefit to placing something big and chunky extremely on one end (and you move around other heavy stuff as well to mitigate)
....but a surface ship only has the planar sea (which it is only partially submerged in) for reaction force. So keeping heavy things as near as possible the centroid is best (for best ship layout design envelope and also turning and response needs). Less heavy things (sensors, payloads, basic structure etc) are better for extremities.
This gets a lot worse in aviation discipline as you can imagine, where there is no steady reaction force provider other than the lift (only) generated by the motion itself.