I agree that my post is not straightforward – It’s both an introduction and a question. But please reread and you’ll see that it already answers all of your questions:

Do you know how many cubic inches (or liters) of space your gear is likely to require? What about the weight of gear, food and water the pack will be carrying? Do you require a frame or hip belt, or is your load so light (15 lbs or less) that these can be dispensed with?

“This will become my go-to bag for trail hiking over 1-7 nights with lightweight gear.”

“The shelter, cooking gear, water filter, etc. will almost always be split with the fiance.”

“The Lightning 45 and Buttermilks are looking good at the moment.”

Lightweight gear, according to Wikipedia, is a base pack weight of 10-20 lbs. 1-7 nights should give you rough estimates of my food weight. I didn’t post specific weights, volumes, and belt requirements because they fluctuate based on trip length, destination, and whether or not I’m hiking solo. The above quotes suggest a 40-60L with ~30 lb capacity with a hip belt (preferably detachable for lighter, shorter trips). Does that sound about right?

Are you bushwhacking or staying on trails (this will affect the need for a durable, but heavier, fabric)?

“Bushwhacking, scrambling, and water crossings are the norm but you won’t find us strapped onto cliffs, in the middle of the desert, or bagging peaks.”

Does color matter? Or a 'stylish' contour/profile? Or could it be just a utilitarian/minimalist bag with straps?

‘Stylish’ as defined in my original post:

“a lightweight, mid-sized, clean-looking, minimalist pack with few seams, zippers, flappy straps, pockets, etc.”

“The Lightning 45 and Buttermilks are looking good at the moment.”

“This means DIY and MYOG mixed with uncommon or striking or modded gear.”