Then there is the use of tabby -- burnt and unburnt seashells as aggregate to mix with sand to make walls. The popularity of tabby in coastal Georgia and the Carolinas was because it was readily available. When you are limited to sand and lots of seashells, you make do with what you have.
If you look at the buildings in the link, you will see that tabby can have a comparable thermal mass to adobe, so that should allay your fears on the insulation.
-houses off the ground, on piers or even stumps, with crawlspace underneath (originally inhabited by chickens, which helped with insect control)
-wide, wrap-around porches, such that the summer sun hardly touches the walls or windows of the ground floor, while often allowing better access to the lower winter sun.
-high ceilings and openable transom windows above doors, allowing heat to rise above the living space and ventilate
-a direct path for cross-breezes to blow through the space in both directions....window through doorways to window.
-high-peaked roofs with a vented cupola, allowing hot air up and out.
-large deciduous shade trees roundabout.
-A habitation strategy that might work even today is closing off some of the rooms for the winter season and focusing on the rooms containing or close to heat sources. If these rooms were in the interior or south side of the space, even better. Also heat rises, so bedrooms above could be passively warmed from heated rooms below.
This may be another benefit of the house raised on piers or posts, with a clear crawlspace underneath....accessible to hens for the termites and cats for the mice!
Bahareque hueco was used extensively on the coast of Ecuador, with some pretty grand examples in Guayaquil, where my wife is from, though they are fast disappearing. It is still promoted as a relatively low-cost construction option, but is considered too poor by many. Bamboo panels are still the predominant exterior wall in poor neighborhoods and in the countryside. They let the breeze flow through, but also the flies and mosquitos. Applying a clay or cement layer to the panel is considered an improvement and makes it difficult to differentiate from a more "modern" home.
Anyway, if my wife and I ever relocate to Ecuador, and we do think about it now and then, I would like to see if I can build a rice hull house using bahareque hueco.
I think the advice and guidance by others is generally outstanding thus far...
In support of that, and perhaps more information for you to consider and learn from, here are some other great posts that may be found useful.
Cob cottage (or other natural owner-built home) from scratch
Cob home in Hot humid climate?
Raised Earth Foundations
Jennifer and I have become very good friends and she live in the "South" as well and has very similar desires and motivations. She may be someone to reach out to for more discussion.
Lots of people are confused about steady state thermal resistance or "r-value" vs thermal "dynamic" mass...bricks(mass) works in just about any climate zone. Take note of the way the thermal couples show two different resonating thermal frequecies on the inner and outer brick surfaces that never thermally bridge.
Last I talked to the Director there about a year ago they were trying more insulated brick used over in Europe that did not meet US code yet to modify the dynamics. One could always create a double wyke with a mineral wool rigid board core if they could afford it.
The outer surface can be sealed with a siloxane or silane or hybrid of both from a natural silicone raw material in the form of organostructured you obtain from a local concrete or masonry supplier you gun or pump spray for about $25 gal. You want to do some color test it is a clear coat.... that would produce a water resistant yet 100%+ permeable outer layer that dries, protects against UV, water damage from freeze-thaw, efflorescence, reduce hydrocarbon bonding, provides abrasion resistance, and provides a scratch coat for mineral based permeable paints if desired.
Or you increase the binder ratio or type, or modify the composition to fit your climate zone. Use alot of binder in the outer wyke, less in the inner, or, use alot of binder in the outer and a very permeable plaster/& wood on the inside in a single wyke.
Most of what you need is right in your back yard
Other great choices here in the US are Durisol or Faswall basically double wykes and insulation core thermal/brake, magnesium/clay/sand CMU/ICF blocks with a mineral wool core that are very DIY friendly.
Note: If you want to read about siloxane test data on clay, lime, masonry, Durisol, Faswall, read this thread: http://www.permies.com/t/43637/natural-building/Breathable-Walls post dated 1/30/14....
Based on Minke’s and Straube’s earlier tests, siloxane appears to have little or no effect on the vapor permeance of cement, cement:lime, lime, and earth plasters while almost eliminating water absorption. The use of siloxane can be recommended based on these earlier tests. (better than lime per report..they make low VOC)
Linseed oil and lime washes are not as effective. I tried it before on rammed earth, it darkened it or turned it white. I finally tried an acrylic that worked great at shedding liquid water other than the VOC. Siloxane is very low voc less than 200 grams/liter and it's water based. It should last for decades or as long as the clay it is bound to is there based on penetration depth and the way it bonds.
The outer surface can be sealed with a siloxane or silane or hybrid of both from a natural silicone raw material in the form of organostructured you obtain from a local concrete or masonry supplier you gun or pump spray for about $25 gal.
Can you confirm that all that stuff fits under the broad description of 'natural building'? It's far from my area of expertise, but it seems to be far from the sort of thing that permies.com would wish to promote. Maybe I'm misunderstanding.