I ended up exchanging some emails with Scooter West. They could not provide me with a detailed picture or drawing of the backside and sliding mechanism of the 2nd screen. My main concern was if there would be enough space left for the RAM mount to position the Garmin GPS while still being able to slide the screen down. The answer was that there should be enough space.
So I broke down and ordered the FACO Twin screen for my 2019 Vespa GTS hpe.
The hardware is decent but the instructions are non existent. Watching some Youtube videos was helpful. It takes some puzzling but with some common sense and experience it all came together.
Putting the bolt trough the long bushing puzzled me for a while. It only went in for 1-2 inches but then got stuck.Turns out that a quick tap with a hammer pushed the bolt trough.
The most important thing I learned from Mr Robot was that the expansion nuts need to be pushed in all the way. It took a couple of decent taps with a hammer to drive them inn all the way before tightening with an 8MM Allen wrench (not included).
The plastic nuts to mount the screens are very soft so be gentle while tightening them!
My scooter lost its cool sleek look and has been transformed in very nice looking travel machine with the windshield and the bag on the luggage rack.
Unfortunately mounting the Garmin GPS with the RAM mount interferes with the sliding windshield. I cannot slide it all the way down neither can I position it where I had it in mind but I think it worked out ok.
I connected the power supply to wiring to the USB ports I had in stalled and routed the wired trough the opening for the left mirror. No need to drill holes
Tomorrow I will take it for a test ride to see if the windshield prevents the wind from swirling under the face shield causing my eyes to water like the Niagara Falls.