This part of Radfall can be a little unintuitive at first, particularly for new players at lower levels. The idea that you don't get your strength bonus without a backpack can be a little hard to wrap your head around at first. As of 7.0.7, LitR adds a starter backpack just outside Vault 111, and if you don't like the system the easiest configuration tweak is to just disable the Survival Carry Weight penalty in SCM. If you're using Radfall in your own modlist, I suggest making those two changes as well if you want. LitR users should also be aware of the Salvage Beacons mod, which the included Radfall patch gives you as a reward for the minutemen questline
Your bonus carry weight from strength is unlocked by gear. You get 10 carry weight per strength, up to the maximum total carry capacity granted by your backpack and pocketed armor mods.
Equipped Armor and Clothing weighs 5% less per point of Strength
Strong Back Changes
You get the Run While Encumbered effect of vanilla Strong Back 3 for free
SB1 Now heavily reduce the amount of AP required to run while your weapon is holstered
SB2 +5 Max Carry Load per Endurance
SB3 Runninq while encumbered no longer costs AP while your weapon is holstered
SB4 +10 Max Carry Load per Endurance
SB5 In vanilla you can fast travel, in survival you no longer take periodic fatigue.
Lone wanderer no longer grants a carry weight bonus
Being over encumbered now damages your Fatigue, instead of your Health and Limbs.
How much fatigue damage you take scales with how encumbered you are. The more you're over the limit, the more fatigue damage you take. When you hit minimum fatigue, it will start to damage your health.
Companions Humanoid companions now have a base carry weight of 50 (down from 100), this should be enough to manage their gear
Non-humanoid companions (Codsworth, Dogmeat) now have a base carry weight of 10, they don't have much gear to equip.
The vanilla bug where companions randomly get a huge boost to carry weight has been fixed
Backpacks and Pocketed armor mods should work the same as they do in vanilla on companions.
Carry Weight is extremely janky under the hood in the creation engine. I've fixed as many of the vanilla bugs as I can, but there will always be work-arounds and exploits. If I could rip out the entire inventory system and replace it with a grid based on, I would, but sadly that isn't an option. This is as close as I could get to that in terms of making the player engage with carry weight in a meaningful way.
This is originally based on my mod Loaded Out. There have been a few changes under the hood as part of integrating with the perks module of Radfall, but the user experience will be extremely similar for anyone who's familiar with that mod.