Janette Raven

For fabric definitely go with wool. Stays warm when wet. If it is tightly woven it will resist both wind and water....... think of a new Zealand Swandri.
Pretty much the perfect garment. Generations of sheepies and NZ cow cockies swear by them.
In the case of the sheep, the swearing is perhaps better not translated.
er... possibly also the cow cockies.  Tho perhaps you would not understand the dialect.
To make your own Swandri like garment...
First research Swandri pictures for ideas (internet)
Lots of pockets where you want them.....
Then go secondhand shopping... you are looking for a tightly woven old woolen blanket or rug. Bigger rather than smaller, if possible.
I bought one a week ago, it cost a magnificent $5 and came from the pet blanket basket, rather than from the expensive end of the store.
Right on my budget.
And recycled, so low carbon pawprint.
It was a herringbone weave with two layers, the herringbone layer and an under layer that was more or less felted and bonded to the first.
Perfect from my purpose.
If the blanket has a hole (like mine did)- no problem..... just mend it with wool after you cut your garment and before you sew it together.
You can use a pattern, or create your own from a garment you already have and like, but to do this, you have to know what you are doing.
I like the Landgate Parka pattern, which I have made a couple of times.
You can see it here- https://merchantandmills.com/uk/the-landgate
It is a pretty easy sew, and the raglan style sleeves make for extra comfort. Plus I like the gusseted zipper in the front hood.
Actually I turned my rug into a pair of overalls as they are a much loved garment of mine. They keep you super warm in winter, you can even tuck your hands into the front bib.
There is no pattern because I make my own, based on a couple of garments that I like.
I wish I knew how to post a photo, but I have a Chromebook, and I don't.
We in New Zealand are expecting the arrival of winter any day now.  My gorgeous finished winter overalls are hanging on the wall and ready for their first wearing. They are an adorable light brown wool with aflowery pink cuffs, side/armhole binding and straps made from Indian cotton placemats and Japanese kimono silk scraps.
Very eclectic and me.
Have fun with your sewing projects from New Zealand where strange things are emanating from a beehive full of persons who should know better, and do not seem to be serving the common good.

Sewing stretch fabrics with a straight stitch machine
(in reply to R. Ranson)
- is easy, just stretch the fabric as you sew, that way the stitches do not pop when the fabric is worn and stretched.
hugshugs from New Zealand where the weather is acting strangely and the economy is being weather impacted.

using a copper mordent many plants will yeild a green dye, and some lovely broken greens too.

I am in agreement with Cristo Balete-

"I have clay and love it.  It is only a problem when it dries out, so it should never be exposed to the sun.  Thick, thick organic mulch 4-6 inches to start, or 3 inches of wood chips (as opposed to bark chips) maintained at those depths will keep it workable and great.  It's high in minerals which improves the nutrition of anything you grow in it.  It holds more water so you don't have to water it as much as long as it is mulched thickly. "

My thoughts are..
Compost. Compost. Compost.
Mulch....mulch....much. Work organic materials into beds whenever possible...
Fork over areas before doing anything on top, like a modest raised bed or hugelkultur....
By forking the area (gently rocking the fork once inserted, and not turning.... just loosening the earth) you will effectively double your topsoil later, gaining more water and air penetration, and giving your plant roots a chance to do the real work of creating soil that is to their liking with the help of their friendly little bacterial and fungal friends.
Anything you can do to promote the presence of fungi, such as adding FOREST (partially or fully decomposed) LEAF LITTER to your compost or beds. This will promote aerobic conditions in the beds. Your enemy with clay is anaerobic conditions which strengthen the bad guys and weaken or kill your plants...
I think the proximity to septic could work either way. I know a very respectible plum tree that adores it's spot right by the septic.
The key would be to ditch conventional soap products throughout the home in favour of naturals like vinegar and baking soda (laundry). There will be threads on this somewhere.
Lastly.. I personally would recommend working with the biodynamic preparations, especially Preparation 500 in spring and fall. This alone could make a tremendous difference.
I think you have an opportunity here if you like the site and it has great access.
Hugshugs from late springtime new zealand where the garden is drying out after a plethora of rain, and several baby birds are hanging out hoping for the Miracle of Flight to suddenly happen.