I have done this with an AR300M and LEDE 17.01.04, building my own firmware with Imagebuilder. I left nothing out and included mini-DLNA and all the USB storage packages in the compressed image (on the 16MB NOR). The trick is to build it into a basic image so it is all compressed in the flash. This would work in theory with the MT300N-v2 but unfortunately LEDE does not yet fully support the mt7628 chipset.