Do not use cheap, standard extension leads. They can overheat and melt under the continuous high load of an EV.
A "granny charger" is the portable, 3-pin connector cable used for electric vehicles, usually drawing around 10 amps. Because it is designed for emergency or temporary use, using it outdoors long-term requires strict safety precautions.
A "granny flat" or studio is an affordable way to add living space, often featuring designed indoor-outdoor flow (alfresco areas) to maximize small footprints. Alfresco Design Ideas for Sydney Homes