The Enlightened Equipment Copperfield Wind Shirt comes in a 2XL and is supposedly sized a half size larger for layering. I have no personal experiences, but it may be worth a look.
https://enlightenedequipment.com/copperfield-wind-shirt-custom/
Maybe give a Seek Outside Gila 3500 or Divide 4500 a look? They’re integrated on the 24 inch Seek Outside frame and can handle 80 lbs. no problem. You can even add frame extensions for extra load lift if needed.
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I forgot to mention that my Gila legitimately meets...
It’s probably worth mentioning that there are lots of weights of Xpac out there. I believe Kifaru uses VX21 on their Muskeg Packs and SG uses a heavier duty X42 on their frames.
Here’s an intro to Xpac from the Seek Outside website...
https://seekoutside.com/blog/xpac/
You can have Ron make your MLD eVent Soul Bivy with a full length, two dual sided pull zipper I believe. I think they’re running a 10% off Black Friday sale this week as well.
Why not just pick up a Seek Outside and be done with it? Their Gila and Divide both come in around 3 lbs or less and range 3500-4500 cu. in. (like the pack options you presented), but are also capable of carrying 100+ lb loads. You could even add a Revolution Frame Panel with compatible SO bag...
I think they referred to the Muskeg Bags as their “new ultralight bags” on Instagram.
Kifaru on Instagram: “Here’s a quick video outlining the features of our new Ultralight Bags! We should have these up for sale in the next couple of weeks!…”