Tony, that's only going to change the image's colour balance. That's not actually going to improve contrast at all. Light pollution filters actually block ranges of wavelengths from ever getting to the camera, so hopefully what you do get is only the signal from your object.
UHC filters tend to let through just O3 and Ha wavelengths (though they may be quite broad peaks), so a fair bit can get lost. I use a Hutech IDAS LP2 and it doesn't have all that much rejection compared to a UHC or CLS filter, it does let the reflection nebs through.
Ultimately nothing bring back a truly dark sky except for turning the lights out.
