I only use elastic straps at the shoulder Bridge. Everywhere else i am using non elastic nylon straps.
For me that works great, everything stays in Place.
That Helmet build looks great. The Ears are looking very good. Great Work!
The Sniper Plates also looks good. Just as said, trim a little bit more of the return edge.
Looks great, you are on a good way! Keep on going.
Trim the overlaps an make it fit to your Body. That way it looks much cleaner.
For me, I had to add some side pieces, to close the gap