I now have a usable pedalboard with channel 1 for guitar and channel 2 for mp3 backings.
I generally create my backings as MIDI files with GM sounds, which I have to render to mp3.
This mp3 take up a lot of memory space on my IPad. MIDI files would be leaner.
I wish to create only one plugin for all GM instruments (sf2 instrument base).
For drums (Midichannel 10) you could leave the existing FluidGM plugin.