I previously towed with a VW Touran and Skoda Yeti, so similar mirror design and I used the Milenco Aero with optional extra clamping foot for VAG mirrors.
I now have an Audi A3 and use the EMUK mirrors. They are without doubt the best you can buy. I set them up 5 years ago when I bought my Audi and have spent probably less than 30 seconds tweaking the fit over the subsequent years. No UK dealer supplies them so you will have to get them imported.
I bought off ebay, but you can start your search here. https://www.l-parts.de/ You will not regret the hours you will spend in sourcing a pair.
Colin