In the far west you will find lots of parks that have not been upgraded, so it is going to be very possible you will have a tough time finding places to park. Not to worry though there are lots of private parks for you to visit. Start with a paper map and a pencil and note pad. Pencil out your ideal route, Then go to web sites like rvparkreview.com and start looking for parks and find ones that will accommodate you. The mountains of the west can have snow any month of the year. However summer snow storms are rare most years. September will also start to cool down, so bring a warm coat and long pants for those cool mornings. Most of all bring a smile and have fun.