The problem in the Portland area is that the UGB keeps expanding, resulting in development and lighting growing like a cancer. Filters might work today, but in five to ten years, nothing might.
The filter I mentioned is a comb filter, transmitting the Hb (486.1nm), OIII (500.7nm), Ha (656.3nm), NII (658.4nm), and SII (672.4nm) wavelengths, while removing UV (<410nm), 440nm, 550nm, 590nm (LPS), and 635nm. The spectral output of LED street lighting has a significant blue LED component at 440nm, that is blocked by this filter. LED lighting also has energy centered at about 550nm, which is also blocked by the above filter, and while not a peak like the blue LED, is spread with energy comparable to the blue, towards 500nm and 650nm, fortunately with a null near OIII.
So, given all of this, the most important question is will it work for you? All, I can say is maybe and it depends on what you want to see. I suspect, based on my experience, that it will help, and will continue to help even with LED street lighting, but it really depends on the overall luminance in your area.
I'm not promoting the Orion filter. There might be better ones out there. I would buy another one with similar comb characteristics if I knew of one.