I didn't read most of this thread, but I'd definatly like to throw in and agree with the original poster.
I sometimes see customs that makes me question why someone would do something.
The biggest pet peeve for me, but I never mention it because, hey, it's your costume. But, if you want to fit into the timeline there are a few things that need to be recognized.
First off. Mandalorians hate Jedi, they hate everything about them and everything that represents what a Jedi is. So, when I see a Mandalorian Jedi, it kinda twists my nipple. A Mandalorian would never use a Light Saber for several reasons. One, even as bad ass as Mandalorians are, they just don't have the focus and force power to use a Light Saber, here is a weapon that takes years and years to just get the feel of, and without the Force, it's extremely hard to do. Not saying that it can't be done, it just in all actuallity of most of the stories that I've read, wouldn't happen.
Second, It has been stated in almost every source book...No Two Mandalorian Armors look the same. So, there's absolutly no reason why all the costumes should look the same. You could be wearing football pads, and as long as "look" Mandalorian...hey, you're a Mandalorian. If you pick up issue 7 of Star Wars: Knight of the Old Republic comic book series, there is an excellent example of pre-dated Mando costumes, and I loved it. I got some great ideas for my next custom based off of that one comic book, and it's going to be a bad-ass Mando costume when I'm done.
Three: Regardless of what you've heard Jango Fett was not the last Mandalorian. There were several of them that were used as Training Commanders for the Clone Troopers. Jango provided the DNA, and the Mandos that he hand-picked trained the commando squads.
In the latest book, we see several Mandalorians.
Four: Mandalorians are not a "Race" they're a warrior tribe. Anyone can become a Mandalorian, in fact I saw a Twi'Lek Mando in this story and I thought he looked awsome. So, if you want to be a Ghamorian Mandalorian, that's entirely up to you, and nobody but big GL can say anything otherwise.
And the way I see, when GL released Star Wars, he gave that universe to us. It exists in our imaginations, making us the controllers now. Just because he says "Oh, no more Wookie Jedi." Doesn't mean you have to listen to him. If you want to be a Jedi Hutt, then that's your thing. Nobody has the right to take that away from you.
That's all I got to say. I'm sorry if I upset anyone with my points of views, and I could be wrong. Maybe you're Mandalorian killed a Jedi and took his saber. That's your story, your character...go on with your bad self.