A four inch newtonian reflector...?

Has a focal ratio of 400mm. I have good skies for observing, only one problem, a streelight which is in the way. The only way I can completely escape it is to go behind my house but then I am limited to only a part of the sky. But many stars are still seen. I live in a sub-urban town, pretty far from the city. Anyway, I am deciding on an Eyepiece, either 5mm or 6mm (80x) (65x). Which would you recommend? The magnification of this telescope is more than 200x, but I think even less than mag and the image will be blurry.