Have you looked into the surprisingly numerous squatting, on-the-grid options in easily accessible villages?
There are quite a few full or semi-squatters around, sometimes in really old or abandoned buildings like the family living in the Shek Li ex-sanatorium for years, sometimes in empty but great flats above Hung Shing Yeh beach with seaview and Internet, like the German overstayer (who' still in prison, nabbed at the airport when going on a "business trip"?) There are quite a few nice, but unoccupied places around, empty for various reasons like the landlord trying to sell, waiting for the market to go up even more, or he's emigrated and can't be bothered to assign an agent or caretaker, or has almost forgotten about some neglected place his family has owned for decades, but would need some serious, expensive renovations to rent or sell it, or places under legal disputes within the family or unclear ownership, often dragging on for years through the courts while their formerly nice, often furnished flats remain empty.
And what happened to all the semi-legal, low-cost housing provided by Pinky Chan and other "slum landlords" before? Some of those tenants are still there, staying on at no or very low cost as their huts or pretty old buildings are OK to live in, but not quite legal and not officially permitted to be rented out.... People you see almost every day on Main Street are in long-term situations like this. These places have electricity, Wifi Internet (probably sneaked from a neighbour), water, sanitation, even aircons, and some are less than 20 minutes from a ferry pier.
To conclude, if you're willing to compromise on flat quality, legal status and dubious morality ... and are ready to be evicted at short notice, then your rent can go all the way down to zero on Lamma....
Note:
The above is just for readers' information, but does not constitute my endorsement or recommendation of these low/no-cost rental options.