If any of you are interested, I released the first version of my VG99 layout for Midi Designer. It leverages the full midi Sysex commands to surface way more controls that you will use in the patch creation process.
Please bear with me though, this is the FIRST version, and there is a way to go to make it really rich. For now, it really helps with exploring AMP/MIC/Speaker combos and basic mixer settings.
Hope you enjoy and maybe provide some constructive feedback.
Blog Post with Screenshots, Layout and Explanation here