In the PNW the closer you are to the coast the more mild it will be. The coast actually stays in a range of about 50 in the winter to 70 in the summer. So if you leave Bend (quickly, as it could get snow in October) you could do a fast drive past Crater Lake before the winter closes it down and then follow the Umpqua river to the coast.
Lots of great state parks in Oregon that are right on the coast, a walk from your RV to the beach with your morning breakfast. One Oregon Governor had the foresight decades ago to make all of Oregon's coastline public land. We stay at Nehalem Bay State Park near Tillamook, Cape Disappointment just south of there, and South Beach State Park which is just outside of Newport Bay. All of these are right on the beach, and there are a ton more we haven't had a chance to hit yet.