Seeing how your floor has been raised, along with looking at the pictures of the Audi spart tire/rim you've posted, make me wonder out loud if the offset of that rim is correct & safe to drive with on a Stelvio.
For comparison to your Audi rim/tire, here's a pic of my OEM A-R Spare rim/tire and a 20" A-R rim
Also, here's a YouTube video I found that shows (at the 8:20 mark) how the inflated spare should look when installed on the front axle.
Have you performed a "dry run" w/ your Audi spare? Inflated, installed it, and driven with the spare on your Stelvio? Probably most important, have you tried it on the front axle?
Check it out, I'm asking all these questions because I recently had to use my A-R Spare Tire.
When I pulled out from an emergency repair area and into freeway traffic, the car handled exactly like it handled with the stock 20" tire/wheel it just replaced. If I hadn't just swapped out the tires on my own, I would have never known the difference.
Link: Spare Tire Question
I hope that all this info helps you (and anyone else reading this post) in establishing if your Audi spare tire solution is a safe alternative to the factory A-R spare tire option.