I haven't seen anything like that, and doubt I would use it.
However I noticed there is quite a variation in saddle rails so you might be able to find another manufacturer that has a more adjustable range.

I have rotated seat posts in the past to close the gap between the seat a bars (for growing kids).

---

Training Tweets: https://twitter.com/Jagersport_com
FM Sports: http://fluidmotionsports.com

https://www.amazon.co.uk/...7521753081&psc=1
I imagine you could modify one of these to achieve what you are after.