@Heydude, the PC16-05 is a bog standard XT compatible (it has a Multitech PC/700 mainboard)http://messui.the-chronicles.org/comp/multitech.pdf
Any generic DOS version should work on the -05.
The -11 is a different beast with a different bus architecture, I can't help you with that.
This archive https://dl.dropboxusercontent.com/u/55419307/Siemens%20Sicomp%20PC16-05.rar
contains ROM dumps and photos of my PC16-05 as well as a bootdisk created from the DOS 3.3 on its harddisk.