I don't think there are too many characters. I am generally bad at remembering names and characters but so far I have had no issue recalling who is who and what their role is in the story, and I've read each chapter only once. Most of the characters get exactly the scenes that they need.
But I do think the whole "vacation" with Shane killed a lot of the suspense. Trev's circumnavigation has basically ended in Western Australia. He has been in the same place for 30 chapters now. I understand that you can't rush a romance, but for me the romance completely took over the rest of the story. Each day they spent together was described in detail. And then there were the panic attacks, which were interesting and understandable at first, but then later just became another plot device to bring him and Shane together. Now don't get me wrong, I loved reading about their time together, I just don't think it mattered all that much in the grand scheme of things. As a reader I was always, and still am, way more interested in what the bad guys are up to, Trev's parents, the search for Ares, etc. And most importantly, having Trev complete his circumnavigation.
So for me the issue is not that you write too much, but just the direction you chose to go with the story.
Also I loved the scene with Kline and Fowler, there is absolutely no reason to shorten it. I wouldn't want you to omit any of the scenes with the supporting characters, They are usually my favorite ones.