|On the kuruma 3rd brake light fit great into it and required no sanding or trimming to make it fit perfect just fit nicely on mine... ( this was 2012) I can't speak for newer versions...
I have installed 2 ionic dynamics in last 2 years on different TTs... one with sanding around the 3rd brake light and one called it "best as" and it sat a tad crooked... The ionic I like to install with the 2 nuts on the back alone, and not drill into the hatch as the instructions suggest to. You can adhere it with Sikaflex 211 black sealant all around and it will adhere great.
Id go with the Ionic honestly at the price point , but keep in mind-
1- Pre fit the 3rd brake light (sand where neccesary) and get your holes drilled and fitted before paint for the screws.
2- Drill a hole for the wiring harness in it also as this is not pre drilled either.
3- Use only the 2 rear nuts to mount the spoiler.. Use sikaflex all around it to adhere to the hatch. Do not drill holes in the hatch as they are unnecessary imo.