What the hell do I know, I still use an external fram pack. ;-0
I didn't own an internal frame pack till a few years ago.
Now I only seam to do short 1 to 2 night photography hikes. Most of the hiking gear I use now is ultralightish, but my pack still weighs allot. That is because of the photographic gear, 20 to 40 lbs worth. I also usually carry all the water I need for the hike.
Last overnight hike I used an
Adventure Medial Kits Thermo-lite bivi sack plus 1/2" foam pad instead of a sleeping bag and tent as a test. First issue is it doesn't breath so any moisture builds up.

It was plenty warm, wearing a couple layers of clothes, for a 30F night.

The foam pad is to insulate between you and the ground. The sack can't do that. I also use the foam pad to line my backpack to protect the camera gear. Due to the moisture buildup I wouldn't use it more than a couple nights. I had to change socks in the morning due to mine getting wet from pooled condensation. Also the initial evaporating of the moisture in my clothes when I got out of it made me feel quite cold for a good 20 minutes. Changing into a dry set of clothes in the morning may have been the best way to handle it, but that means two sets of clothes. I do normally carry two sets. Set two is an emergency set that also serves as padding for photographic gear. I've dunked one to many times in an icy mountain stream to not have a dry set of clothes along.
I pack everything inside dry sacks. I usually use 3 to 5 on a hike. One is for food and toiletries only. No other sack has food in it and I have never packed food or toiletries in any of the other dry sacks. One is for food prep equipment. Often now I no longer take it. One is for the med kit only, it's red. The last one or two are for clothing, camera gear, and anything else that can't get wet.
Food is boring for me. My current hikes are only 2 to 3 days so I only take CLIF bars, nuts, dried fruits, and dried meats. Nothing that needs any preparation. It also has the advantage I can easily eat it while moving. For the nuts, dried fruits, and dried meats I prepackage them into roughly half hour energy burn quantities*. That way I eat two an hour just before and while hiking.


Makes meal planning quick. No stove, pots, or dishes, but 4 oz of 95 proof drinking safe alcohol. It serves as emergency fire starting fluid and wound cleaning.
* Go find a calorie burn calculator to figure out who many calories you would burn per hour hiking. It is different depending on your weight. I would include your gear weight.
This calorie burn calculator says I burn 750 calories per hour hiking. I put in my weight plus pack weight.