Pentax

Simultaniously taking photos and observe will not work. You can do either/or, not both at the same time. Because the light either hits the mirror and goes to the eyepiece - or it goes straight through the Flip Mirror housing and hit the sensor of your camera.

The filter itself will work as desired. But SII is in the deep red, at around 672nm. So, with a colour camera with RGGB Bayer matrix, only one fourth of the pixels are sensitive for red. That's why a monochrome camera will always be much more sensitive for narrowband photography: It collects the photons with all the pixels, and not only with those which are sensitive for red.
RASA and Hyperstar are more fun with a colour camera and a broadband filter like the new UHC-L (which can be pretty good against LED lamps), as you can then use the whole sensor in one image and don't need to swap filters. If you really want to go into narrowband photography (no matter with which filters) due to high light pollution, a monochrome camera is superior.

Please see following link to a holder for tube diameter from 48 to 72mm
https://www.baader-planetarium.com/en/baader-multipurpose-finder-bracket-mqr-iv-9x60-finder-(max-diameter-72mm).html

Our 2" Filters have a clear aperture of 46mm. Our equivalent to the L-extreme filter would be our UHC-L Ultra L-Booster Filter: https://www.baader-planetarium.com/en/baader-uhc-l-ultra-l-booster-filter.html

For adapting any cell mounted Baader 2 inch Filter onto a camera lens with 52mm front filter thread you will need:
#2408166 Baader DSLR 2" Filter-Holder M48 / SP54: https://www.baader-planetarium.com/en/baader-dslr-2%22-filter-holder-m48sp54.html
#2958052 Baader Lens-Adapter-Ring SP54 / M52: https://www.baader-planetarium.com/en/baader-hyperion-dt-ring-sp54m52-for-dtadapter-iiandiii-and-hyperion-eyepieces.html
Based on the SP54 thread, we offer many more adapters for various camera threads, our so-called Hyperion DT-rings. https://www.baader-planetarium.com/en/catalogsearch/result/?q=sp54
Please check out also our Digiscoping Brochure: https://www.baader-planetarium.com/en/downloads/dl/file/id/444/product/0/digiscoping_camera_adaptations_for_afocal_photography_and_eyepiece_projection.pdf

Its more a photographic tool. You can use it visually but its not very satisfying because you see an obstruction on the outside and the image is more concentrated and therefore brighter which affects the visual surface contrast