Do I need to bring my 10-20mm?

My wife an I are heading out on a long roadtrip next week. We'll be visiting several US National Parks (Grand Canyon, Bryce, Zion, Joshua Tree, Yellowstone, Grand Teton) as well as Route 66 (OKC to Flagstaff only), Sedona, the entire west coast and taking an Alaska Inside Passage cruise. Since we'll be in some prime dark sky areas, I figured I'd try my hand at capturing some stars. I'm trying to decide which lenses to bring without making my bag too heavy. I have the following:

Canon R50 (and an EF-RF adapter)
Opteka EF 6.5mm f3.5 fisheye
Sigma EF 10-20mm f4-5.6
Canon EFS 15-85mm f3.5-5.6
Canon RF 100-400 f5.6-8

My big questions are:
1. Do I really need to take the Sigma 10-20? Will the extra 5mm gain me that much over the 15-85? And is that better than the 6.5 for night sky?
2. With the 100-400 (which I just got yesterday) can I just leave my SX40 point & shoot (that goes out to 800mm optical) home? or will that little extra distance really help with wildlife?

Thanks in advance.