Fifth wheeler trailer - how hot/cold does it get?

Thanks for the heads up. Hopefully other sections of the road can be driven at 50MPH and not 25MPH... We're going to take 8-9 weeks for the trip, so we won't be in a rush. We want to stop and do a lot of sightseeing and some hiking along the way too. There will be some parts of the trip where I hope to just drive through (places we've already been to in the past - between Seattle and Jasper, AB) and I hope to cover 400 miles a day on such days (two drivers, so we'll take 2-3 hour shifts).