Switching presets from AU host

(Hopefully) a short question. To make switching between VSTs easier and faster I run them all as instances in mainstage (also for the better reverb and such things). The computer has 16GB of RAM, but I'm about maxed out on how many things I can run at the same time.

Here is the question: In standalone mode, PT has the option to map midi controls to next/prev instrument and next/prev preset. Unfortunately it doesn't seem to provide those options in plugin mode to the host (mainstage in this case).

Does anyone know of a way how to do that? Preset switching is nearly instant in PT, so there really isn't any need in keeping a complete PT instance for each instrument / preset. Would be better if I fill the ram just with sample based instruments that need to be loaded.