DeepEvil,
Not sure if you saw this thread:
http://forum.mikrotik.com/t/wireless-vlan-trunking/95167/12
Also, I am currently building an SXT 5ac Lite ↔ SXT 5ac Lite bridge using the Bridge / Station Bridge mode. In my testing it seems to preserve the VLAN tagging through the bridge without any specific VLAN configuration in the bridge itself.
I am using this article as the basis for my SXT ↔ SXT bridge:
http://wiki.mikrotik.com/wiki/Bridging_Networks_with_SXT
Good luck!