You will not want to pick any missions ranked 40 or up. Those tend to have gunboats showing up, if not giant waves of bombers; 39 is borderline in terms of larger vessels showing up.
And yes, the missions can be incredibly rough but they are still do-able. Dijon Station has a good number of missions that are lower ranked, and the payoff is usually large enough to still make a profit despite any potential damage sustained (aside from being shot down).
Maybe some day, they'll see a hero is just a man who knowshe's free.