FWIW, been running around Bellevue, Redmond, Seattle, and all over the North Sound region for the last decade without a front plate on any of my cars. Been pulled over a few times, front plate never even came up.

So while I have no doubt that it's in the books, it still seems to be lightly enforced. YMMV, but I've found that not being a creep to the Officers goes a long long way.