I have an SD of 4GB and an microSD of 16GB, like i said I need the .cia only for 2-3 games, nothing more.I'd say use NASA. It is significantly more recent than devMenu/BBM as far as I know, and works well enough. I also think it doesn't have that issue BBM/devMenu have when the SD has more than 100GB free.
I'd say being a legal app is a good reason, but people installing warez probably wouldn't care less x.x
Also I don't even have the homebrew channel on my 3DS, is this NASA require it? it looks much more complicated than BBM.
In meantime I return to the original question: can I install only the game .cia with .3DS BBM?
Thanks!