have you thought about pulley systems and growing in trees seen that done many times with success
i mean who the hell walks around looking up all the time
most people take no notice of whats around them and autos can easily be concealed if you use the right strains and just use 1 plant per briar patch .
mossy's purple jems don't smell to much and outside are pretty damn stealthy
also growing along the side of motorways isn't a bad choice as people don't stop
the highest problem that faces the guerrilla grower is watering the plants rivers and lakes all attract people so make them almost non viable options
take a look on google earth and see if you can spot a decent location