My wife and I will be hiking in North Cascades and later in Mt. Rainier N.P. in early July 2018. We are from Cincinnati. Will we need hiking boots or can we just use our cross-trainers if we want to do "average" trails. We will probably stay away from snow pack trails. Is there an issue with sliding on gravel with "gym shoes"? In addition, we only have bulky winter coats here or light weight jackets for our winter wear in Cincinnati. We are considering buying "technical" clothing ( light weight down filled jackets ) that can be compressed into bags while hiking if it gets too hot. A waste of effort or not? It is hard to get temps at altitude (inside the parks at altitude ) for the summer period or maybe I haven't found the right website.