Itasca Sunova TV antenna Coax problem

You will likely need to pull down some portion of the ceiling or taking a new route from the power supply to the roof. That would require a new small hole in the roof which would be simple to seal but it may likely be a much better option that going into the ceiling. The wiring is tied into the factory wiring harness and cannot be used as a pull (I believe you have already discovered) so the only option is getting access to the entire length of cable or rerouting a new cable.