Rear Crewmember Course
Unless it has changed since I left, when I was asked to help design the replacement to the ADG course, the training takes 6 weeks and starts with an aptitude and grading course similar to the pilots'. We didn't use TA soldiers then because of the pre-course requirements - Junior Leadership Cadre pass, Sigs Class 1 and so on - and the length of the course itself would pose a problem. On completion should there be a way through there would be issues with currency and so on.
If this is what you want to do then get in touch with the potstings bods and persuade them to allow you to transfer to a FTRS or NRPS (I never know which it is) and find a sponsor in one of the German Squadrons. Bear in mind that the training costs the taxpayer around 100k so the argument must be compelling and return of service minima may be mandatory...
Good luck!