Glen,

Don't know which route you're planning on taking to Bend but Wally and I will be rolling down US-395 towards Kennewick early in the afternoon on Wednesday.  It all depends on how far we get into Montana on Tuesday and what time we get on the road Wednesday morning. 

If we get to Big Timber, MT on Tuesday it is about 9+ hours from there to Kennewick.  So if we're rolling by 6 o'clock MDT (5 o'clock PDT) that would put us in Kennewick between 2:00 and 3:00 PDT and then into Bend about 4 hours later.  That may be later than you want arrive in Bend though.