I am coming in late to this. I am currently owner training with the assistance of a trainer.
We have the basics to work on at this time and also remedial socialization as my pup was never socialized. Plans are to get the remedial and the basics done, then move onto the 3 levels of Canine Life and Social Skills obedience training. After that, the plan is to do the CGC. I am not sure if my trainer has anything with a PAT or not, but I can pull up some and let her see. Otherwise, we will move onto task training. Mine will be a Hearing Assistance Dog.
As far as "uniform". While they are not required and GSDs can get warm if the temps are too hot, I suggest checking into specific state laws before making a decision. In my case, where I am now, there's no requirement (that I can see), but where we are moving to in a few years, at this time, does require Hearing Assistance Dogs, (Hearing Guide Dogs) to have orange on. Did not say it had to be a vest or what. I have a cape style vest to use and will also have bandannas.
If people were to follow the law, and do the right thing, there should not be the problem with untrained owner trained SDs. It takes doing homework in finding the right trainer. Some charge very little and some charge more. Some will even do a barter system like mine.
I don't mind certification, but only if it is accepting of owner trainers. Too many things I have seen proposed from various people and such are leaving out the OTers. Also, there are issues with the CGC. Not all OTers live close enough to certified examiners (is that the word I want). In one case, I know this person would have to travel more than 300 miles to one.
I am kind of new to all this, but I felt like chiming in.