I was thinking the same thing..use the pack for a backrest.Colin Fletcher used to do that,written in the hike in the Grand Canyon...Also the chair
base could be slung around the outside back of your pack without too much difficulty...
Camp chairs..lots of options,but do people really want to pack "hard items" to use for those?Thermarest makes a "chair adapter cover" that folds the pad up, with 45 degree straps with clips on the side to hold the back rest so you can lean against it.Unclip it and it folds flat for sleeping.The weight factor is minimal,say a couple backpack type straps and a little material that helps keep your pad clean also..not a bad deal!
I make "gear hammocks",a smaller one for slinging my gear underneath my hammock.

Right now the ends are just a sleeve the strapping goes through to tighten the ends around the backpack or whatever else is slung in them(boots,hike poles,6 pack,etc..) but if I gathered the ends like a regular hammock,they should be strong enough(hung elsewhere) to support a person as a chair when they don't have gear in them..kinda dual purpose.Put your junk in the hammock and use the gear one as a chair until you need it for gear,then move the gear out of your sleeping hammock to the covered gear one under your sleeper at night.
The one problem of course is you need a support system or tree branch over head to use it as a chair,limiting the possibilities of sitting by the fire or camping where the trees are large enough for hanging a chair from a branch..or a line between two trees that would let you move the chair anywhere along that line..Yeah,I've thought about it..
Another option is a hammock chair suspended between two trekking poles,but if I'm using a tent,my poles are usually used for suport for that.Hammock camping would work okay with that idea.
My gear hammocks are usually about 7' long(33" doubled up sides and about 18" for the seat area as a chair...)and about 30" wide which would provide a seat and back rest.I could make them up to about 44 wide..with a weight of about 10-16oz(made with 2-2.5oz per square yard taffeta)I figure with straps,hardware and that.
Just an idea...
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