Great to hear your trip went well and you guys survived the maiden voyage and the valuable lesson learned about the Rockies wx and how fast it can change. From the photos it looks like an awesome trip, congrats! Enjoy that new drift boat, you will always remember that maiden voyage!
Your description of that storm reminded me of a motorcycle trip the wife and I were on several years ago, we were up on the Beartooth Hwy (hwy 212) south of Red Lodge, MT. We could see this huge black storm to the west coming out of YNP so we pulled over and put the rain suits on just in case, but still it looked like we were going to hit the Chief Joseph hwy and head downhill before it hit.........needless to say we didn't have a chance, it hit us so fast and hard that I was afraid to pull over as the visibility dropped to less than 20 ft, I was afraid if we pulled over we might be hit by a car from behind, so we just endured the torture from the driving rain and hail and finally made it down to the bottom safely.