I cant help you much with the under suit question, but I do have some warnings for the helmet. When I first started the forums this was a common topic. The general consensus was that no matter how well made and sturdy our helmets are, we should never use them to replace a tried and true motorcycle helmet. I know this makes me sound like a major kill joy, but these suits are primarily for looks, not seeing which one can endure the greatest beating. I hope you are able to get some better advice on your actual suit. Best of luck.
Thanks! I have also taken that into consideration, for my Helmet I was thinking of using an actual motorycle DOT approved helmet as the base and basically adding on the pieces to give it the look. if that makes sense? Sure the helmet will look quite big but hey I'd rather play it safe. But will also have a regular cosplay helmet to carry with when I am not on the bike Tigerpause on youtube does something similar but with plastic toys, cut them up and put them over the helmet so they the helmet keeps its functionality.