Earlier quoted context omitted.
Powerline Ethernet might be a solution for the cable problem. I'm thinking of connecting the extra AP(s) through Powerline Ethernet to the router if there is no copper Ethernet available.
Powerline Ethernet is not really a good solution either. If you don't use your phone jacks, take the cover off one and check if it's actually using Cat5 or greater. You can then use those for network if you replace the connectors.
Why is that?