Someone should create a "Junk Compactor" mod (if one doesn't already exist) that would allow you to store all junk in it (by simply interacting with it), press a button and have the resulting components automatically delivered to the Workshop of the current Settlement you are in. Since it is a machine with moving parts, it should probably require one power to operate. Optionally, you could get a menu to direct the resulting components (from the compacted Junk) to any Settlement you have already unlocked. If you know a Settlement is running low on Steel and you will need Steel, you could direct the Steel to that Settlement from Sanctuary Hills or any other Settlement without having to rely on setting up Supply lines via the Local Leader perk.
Perhaps (and I don't know how to mod or if this would even be possible) the "Junk Compactor" could even be a portable device weighing very little (either be self powered or operate on Fusion cores, but the Cores would last for a long time before needing to be replaced) and combine the Workshop itself, allowing you to essentially scrap items in the open world environment outside of the Settlements that exist in the game. The Junk Compactor would have a medium radius and you could move just like you can in Settlements and scrap items within that radius. With all the trees in the world, you would never have to worry about running out of wood. There would, of course, have to be some limitations to what could / could not be scrapped. An example of something that would probably work okay is the destroyed car and the tire on the Road between Sanctuary and the Red Rocket Station. From what I understand, there are mods on PC that allow PC players to scrap or at least remove unwanted (eye sore) items from the game world. Unfortunately, since I play Fallout 4 on Xbox One I will have to wait for the eventual release of mods on Consoles.