Covert feedline (small magnet wire suitably camoflaged) from a window down to the clothesline. Nothing says the line could not be some stranded number 14 THHN wire, eh? Tie the ends off through doubled-over six-pack plastic ties as an insulator. I would make the wire white BTW.
Hang a few towels, etc on it for further blending in.
A longwire like this works great - I've been using one like this inside my attic (slate roof over cedar shakes) and with a 20 foot random wire I can run my National SW-3 just fine. There's plenty of signal.
I've been meaning to build a trap dipole for the backyard.
Jim