An end fed long wire is your only possibility given the rules you set
forth... A 5 to 10 wavelength wire should help... Model it or look in
the antenna handbook for the patterns...

However, my "beat the rules instinct" kicks in... What is to stop you
from running open wire line a quarter mile out to a vertical? Even if
you have to go out after dark and stand the vertical up and take it
down at dawn, eh!

denny