Hi, we are going to be at Yellowstone and Grand Teton the last week of Sept. and first week of Oct. We were hoping to rent a boat or canoe and explore Yellowstone Lake and/or one of the lakes in Grand Teton. We are also intersted in rafting trips. Unfortunately, it seems that all of the boat rentals and rafting outfits in the park are closed up by mid-September. Is this true? Thanks in advance for any advice.