The problem with sky glow is that it introduces additional shot noise. You can image in LRGB from a light polluted location but you need to do much longer total exposures to get the same SNR as you can get in a shorter time under dark skies. You may still be able to get decent results for bright objects in a reasonable time but you won't be imaging dim galaxies.
Imaging in narrowband works a lot better because the narrow bandwidth of the filters rejects most of the sky glow.
The gradients you get from light pollution are manageable using software, e.g. DynamicBackgroundExtraction in PixInsight or GradientXterminator for Photoshop.
Shiraz has a nice rule of thumb which you can use to determine an appropriate sub length:
http://www.iceinspace.com.au/forum/s...d.php?t=117010
Cheers,
Rick.