OpenSuse 13.2, Dell XPS 12, Display Port MST support + Secure Boot trouble

I’m testing OpenSuse 13.2 on my work laptop which is Dell XPS12 (Haswell). I’ve managed install it in dualboot with Windows 8.1 and Secure Boot enabled and basically OpenSuse works fine. Windows has Bitlocker enabled and OpenSuse has LVM with encryption.

This laptop has only one mini-DP out and no dock, so I’m using two Dell U2413 monitors daisy chained (Display Port MST). Display adapter is Intel HD4400. This works fine in Windows but not in OpenSuse, second monitor is not detected. I understand that this would be fixed in newer Kernel releases, but apparently there is no newer than 3.16.7 that is signed for secure boot? What would be the recommended way to get both DP MST and Secure Boot support?

I had to do the “Booting the Machine that supports only one signature with vendor provided Keys” when I was installing OpenSuse.