My Orvis (Gokey) duffle has been my constant companion on all hunting trips for 15 years. Very thick green cotton canvas with bridle leather straps and brass rivets. Most duffles cannot be overloaded or they fall apart, mine has had 70lbs or more in it countless times.
It’s my carry-on bag full of binos and my scopes, my lithium batteries, and high-value items. Because it’s unstructured, they never make me put it in the luggage-size-checker cage. It’s always 4x the max weight allowed and I’m never stopped.
Orvis sold off Gokey about 5 years ago. I recommend a vintage Orvis or a vintage Gokey. You can find them on eBay. MSRP was $300ish, I bought at an outlet for $100. Used they sell around $100.
edit: regardless if it says Orvis or Gokey or JW Hulme on it, you want the olive green one. If it is a bit more forest green colored and says Orvis, those are made in China and they’re junk. Search eBay and you’ll both types, same price, know the difference!