Tartarus V2 & Synapse 3 - configuring help needed

I'm probably going to use the wrong terms here, which is part of why I can't find the answer to my issue on my own, so I apologize in advance.

The V2 has more keys than the old Tartarus, which was almost the perfect size for my hand. I've pried off the palm rest (it's too big, even in the "small" setting) and remapped WASD to 09/13/14/15, along with remapping other keys I use for movement and frequent abilities.

What I'd like is to have two different sets of functions for 01/02/03/04/05, switchable when I press and release the thumb button (20). I don't want to *hold* this button or use hypershift.

For example, in World of Warcraft, my default would be to have Tartarus buttons 01-05 be blank, so nothing happens if I accidentally hit them. But when I get into a vehicle, I want to be able to toggle button 20 and load Tartarus 01-05 with a new keymap, while maintaining my standard keymap for the rest of the buttons*.

When I exit the vehicle, I want to toggle button 20 and restore Tartarus 01-05 to the old keymap.

* I'm fine with manually binding the rest of the buttons/arrow keys or copying the settings -- however I have to do it. I don't expect a toggle button to switch *only* buttons 01-05.

On the old Nostromo, you could do this sort of thing with a color-coded shift, though I can't remember the terminology. How can I do this with the V2?

Bonus question: Is there a way to change the lights with this toggle, as a visual cue to remind me to switch my setup as needed? Thanks!