Perhaps I should have said "dust tight" instead of airtight. After my car ( 1989 Dodge Aries K LE) is fixed ( lots of little things need fixed, new hoses, brakes checked, tires rotated, etc.), I'll be traveling some dusty roads. However, I will not be traveling them for hours. I can shoot most nature here within 15 miles of my house.And my trunk is a real trunk, where you have to get out of the car and open it before you can reach into it. Not a hatchback.
As for belt type lens cases, I do not wear belts. Okay, maybe I should explain further what I had in mind. A backpack to carry camera, two lens, and a lens case that attaches to the backpack. Any one know of something like that.
Tamia, I do believe the rucksack wouldn't work for me, but thanks for sharing your idea with me.
Medium FormatPro, your ideas, and suggestions helped me see I wasn't giving anyone what I had in mind as to what I really looking for, so thanks.