Sour cherries are way to sour to eat straight. That is a belly ache in the making for sure.
I cannot grow cherry trees here either. Mine made it to the second year and died. A lot has to do with our deep freezes and I am sure you get those there. Some types of tree are just to delicate to make it. Peach trees are hit and miss here. Some make it but most do not. The nurseries do not guarantee any fruit trees here. They still sell them but with the warning that many do not survive to maturity. Apple trees are the best for my area but still get hit with blight and other issues.
I have had 2 peach trees die on me over the last 6 years. I have my fingers crossed for the baby one and the 3 year old tree this year. Most years even if the tree makes it the late frost takes the fruit.
There are some lucky people here that have huge green houses and grow the fruit trees in there.
Have you looked into the ranges for rainier cherry? I am not sure of its zone rating. I would think the best place to plant up north would be close to a structure on the south side. Still a gamble though.