I never tried combining two filters to suppress haloes.

Let me show you examples of these "haloes" - maybe it's just "star bloat", and this is normally seen with H-alpha images?

Here are 3 test images, taken in 2006 at a place with light pollution readings of about 20.3 on the original SQM. They were taken with a Canon 30D at f/4.9 with a SV80S telescope + unmatched TRF2008 reducer. Mount was a G-11 and autoguiding was used. The target is NGC7000 -- North America Nebula.

These are full-frame, uncropped single subexposures of either 5 or 10 minutes. Usual dark+flat+bias calibration was done in Images Plus. Post processing with Photoshop involved extracting the red channel and replacing the blue + green channels with the red. A single gamma adjust from 1.00 to 2.20 was done using the Photoshop levels function. No other processing was done, except reduction to 750x500, conversion to 8-bits and then JPEG conversion with quality = 9.

1st shot has no filters. 5 minutes, ISO 400, new moon: