Want to stop using synthetic plastic materials while camping.

[walker]

If your looking at sleeping out in very low temperature then I had the Norwegian army issue sleeping bag many years ago , all natural materials and very warm not even a zip on it as it double Brest wrapped and fastened with wooden toggles.
If you want to sleep in warmer climates then the Czech army bed roll is very good . Both can still be bought but they take a lot of finding .

 

[Erbswurst]

The question is only how to attach such a monster to the rucksack.
One could try the Norvegian army cotton rucksack with external frame.

Norwegian Backpack with Steel Frame, Surplus - Varusteleka.com

The classic Norwegian army

www.varusteleka.com

The German equivalent has plastic parts but you can see in the video below how such a rucksack was packed correctly in the military.
Here are missing essential items though because the German army did carry them in belt pouches in the eighties.

You have to press on the word YouTube to see it.

I doubt that this combination will still fit well under the Polish tent sheet rain coat. But it's worth a trial.

 

[Erbswurst]

B5 WWI Replica Boot - William Lennon & Co Ltd

The 'B series' style boots were introduced from 1915 onwards by the Army during The Great War. Our replica B5 boot is produced using the original patterns from a surviving pair of originals & knives found in the factory archives. Fitted to the correct wooden 2181 square toe last.

williamlennon.co.uk