TWLoader on top of nds-bootstrap is the only programm that enables 3DS users at all to load games besides from a flashcard.
And this is using the TWL mode of the 3DS as it was not possible otherwise.
So your suggestions are all not possible to do on a 3DS as the TWL-mode is just a little faster NDS-mode.
So just give up and buy a flashcard or use TWLoader for the time being, there will be no major developments besides TWLoader and nds-bootstrap on that front as there is simply nobody interested in it.
Actually it is possible, the first two ideas are not impossible neither, it just needs a lot of files and processes that are tedious to do. But the third one is even less complicated. (But not simple) lol.
So I'm not a fully trained programmer, I just have the experience that I acquired doing some other projects. But I do know that there's a way to do it, it just need a lot of other knowledge that I have not.
Think that the 3DS CLEAN (without software modifications) is still able to read NDS cartridges, and to play the files send via Download Play. The 3DS has full compatibility with NDS games already. THE EMULATOR IS THE 3DS.
My idea is that, the 3DS should be able to read another cartridge reader if its connected (added to the hardware), the problem with this, is that it would load over the same icon, making it crash and also, I don't look over modifying the hardware. So... what it needs is to be cloned with another ID pattern, and this new reader could be just emulated, not physically added.
When the cartridge is in the slot-1, the 3DS knows it, because it reads the files on it. This will happen with the emulator, whenever it reads the file on a specified folder, it will load.
Everything is already on the 3DS, the files and the slot-icon with his properties, with other elements. With this and a 3ds batch file that redefine the address to read, you can emulate the cartridge reader. But we still need to make it possible to add the icon to the Home menu. To add the icon into the home menu, could be used a .CIA to install the icon (the cartridge software icon is installed on the 3DS, is a software).
To do the last part, you'll need something to make the .nds file, to be inside that emulated slot (that could be handled by folders and bat files in a computer... but I don't know the commands for the 3DS command prompt).
There's another hundred ways in my mind, I will write these down, and make more research, I'll try to do it after I get all the knowledge.
Is not impossible.
I say, that if you don't know how, it's not a possibilities problem, but a knowledge issue.
Thank you anyways for helping with your participation, every little idea is good.