NSPs do have the disadvantage of temporarily requiring double space (which is quite a problem with the larger games) since they have to be on there while you install.
Actually there's a workaround to the double the space if you don't mind a bit of waiting.
Suppose you need to install a 15GB game and you only happen to have 15GB left. Knowing games get installed inside the Nintendo folder on your SD card, you need to copy the extra 15GB needed off your Nintendo folder onto your PC hard drive, then delete those folders you selected from your SD card. That way you will have 30GB which you can use to install the game and copy back the folders you had moved to your PC.
It's a bit of a hassle but it will have to do until a PC installer surfaces.
That is suspiciously small. There are ROM sizes smaller than 2GB, so chances are this is another one that failed. Well, you won't know until after you install and then try it I guess.
Actually that is the real size of the game.