I've recently come across this method of wall construction which seems suited for relatively unskilled labour. The R value for the wall depends on how thick you make them, and how much lime/saw dust you use for insulation between the two skins of masonry. Pinus radiata is readily available and suitable for cordwood walls.
The site I'm considering is the same steep site I looked at for building Oehler structures but this type of construction seems more likely to be consented by the Cilty Council.
There is an example of a cordwood house built on stilts or piles . I presume one could built a suspended concrete slab as the floor. And make it strong enough to support a rocket mass heater. I'd expect the house to be about 30 m2 in size. Maybe a walker cabin stove would suit both space heating and cooking. The location is not very favourable facing away from the sun but I imagine one side could face some sun. So, if that happens to be the case, maybe one can make one wall a trombe wall? However, I've not seen anyone do this.
I would think of any alternative home, a cordwood home would meet approval. there are two ways to make them, either with fully stacked rounds of wood, or in a timber frame where the infill is just the rounds of wood. If passing inspection might be a problem, I would go with the timber frame so that you can show via engineering that it is a sound method of home construction.
This type of home would also be good on a rubble-filled foundation as well, with an eastern floor perhaps. I love concrete slabs because of the way they naturally are geothermal-like, but done properly a earthern floor would net the same results, and either one would support a Rocket Mass Heater.
I like the idea of an earth floor perhaps surrounded by an insulated concrete ring foundation to support the masonry walls.
I had another wild idea. How about using water tanks as the actual wall and secure them to the posts. And then enclose the exterior of the water tanks with glass (old windows), or green house materials to create a trombe wall.
These water tanks are 1.85 m high, 2.4m long, and 260 mm wide.
The rocket mass heater could incorporate a copper coil in the oven part and push hot water to the water inlet at the top of the water tank. A shower would also take the water from the top of the tank and send it pre-heated to an instant gas water heater.
I'd better add this as a reminder regarding Legionella
3.5.2 Where the solar water heater stores potable water and is used as a pre-heater for an instantaneous water heater, either: a) the hot water storage tank connected to the solar collector must be fitted with supplementary heating and a controller operating to meet the conditions outlined in Paragraph 3.5.1, or b) the instantaneous water heater must heat all water passing through it to not less than 70°C.