Washington State route to Las Vegas

My husband and I are pulling our 27 ft Travel Trailer with our Ram 1500 Bighorn from Seattle, Washington down to Vegas on April 2 and at this point plan to take US 26>20>78>95. We thought it would be a prettier drive than I5 and we're returning home via I84 so didn't want to do that again. I've never been on those hightways or through the mountains and forests it looks like we'll be going through and I'm concerned about driving on steep, scary roads, and through snow. This is our second year of RVng so not too many trips and experiences under our belt yet. Our initial planning has us stopping in Prineville, Oregon and Winnemucca, Nv. arriving Las Vegas on April 4th. Also, I'd really appreciate any tips/suggestions or words of wisdom anyone might have.

Thank you!