Hi, I have the 3.1
I use giant support, I find it very good.
I only had to make two more separate holes in the support, on one side are already marked to make them, and the inside of the seat that is made of metal, aluminum is easy.
I leave you three photos

https://drive.google.com/file/d/1K7VQYEgHLIdp68h82_O_GKL9F1m_qh3Y/view?usp=sharing


https://drive.google.com/file/d/1VyXBkrccs2g9fHB7pxqXiuELrPPXLJ4q/view?usp=sharing


https://drive.google.com/file/d/1s-YGQ6HCT1iz6fqtSlMz-mQIgLjlTBl7/view?usp=sharing