From what I know, Pioneeer is Black pipping. So you can get any Heer tunic really and add black shoulder tabs and correct collar tabs. See links ->
http://militarytour.com/Reproduction...er/Pioneer.htm
http://militarytour.com/Reproduction...r/Heer/101.htm
http://militarytour.com/Reproduction...r/HPioneer.htm
If your doing Officer, finding a visor might be hard...