Woah, incredibly splendid mod!!! *.*
How awesome it would be if you could include sooner or later
a, wearable ABC rubber suits
and b, among the GDR helmet versions even a helmet with a standard camo like this
http://www.ebay.de/itm/like/263080961657?clk_rvr_id=1481361745958&vectorid=229487&lgeo=1&item=263080961657&rmvSB=true
In case you want to add more authenticity to your German radio protocols, I offer you to send a realistic (=non stereotypical) transcript (in phonetic alphabet or the standard Latin alphabet; perhaps with recorded phone quality examples) of the lines in Saxon dialect since such a way of speaking was fairly common (eg. Leipzig and Dresden being the largest cities of the GDR after Berlin) and I grew up near Dresden (so it wouldn't be so hardcore Saxon dialect and still generally understandable for any Germanophone), as you wish.
I wish you all the best and muuch fun and success with your plans! :)