It's a big ride, lots of Bozos, the team riders in pace lines are dangerous, stay away from them and NEVER join in their line or they'll run you out. Start as early as you can, 5:00 am is the best time to start. Probably won't have headwinds, usually the winds are north to south in July. You may need a light rain jacket, but don't take it on the ride unless the forecast is sure of rain. Watch out for pace lines passing you at high speed, never pull out left without looking, and be choosy of the lines you join.
I can't help on rental bikes, you may have to go to Portland to rent a bike.