The link to my presentation slides is:
I have tried using a filter wheel but only when doing Lunar and Planetary work. I have not tried using one for deepsky. I instead have simply removed the camera from the scope and changed filters manually. Your concern over light leakage is probably a valid one for deepsky since the exposure times are generally quite long. Light leakage will depend on the design of the particular filter wheel you are using, and whether or not you are able to implement additional precautions like no local lighting and or an extra layer of dark material drapped overtop. If you have a filter wheel meant for astrophotography I would not expect there to be a problem.
Regarding using the histogram tool in your camera control software to adjust the RGB of the image, I am not sure what your question is. If you are asking whether or not you can adjust the histogram to cut out wavelengths of light that we don't want to see (ie. light pollution), the answer is NO. What your camera sees and what you see are two entirely different things. The adjustment you make to the histogram is meerly shifting around the image data coming from the camera, changing how it is displayed between the three colour channels of your monitor. This has no connection to the different wavelengths of light that are being perceived by your camera. There are many layers of translation in between. The CCD sensor sends a string of voltage values one for each pixel to the image processor for further conversion into an NTSC analog video stream (chroma + luminance) that then get's digitized by your capture device and translated into a digital video stream (RGB). So right at the start the sensor itself is already integrating all the wavelengths of incoming light into one intensity value per pixel. The only way to separate out the unwanted part of this signal is to filter it out before it gets to the camera.
Now if you are asking if one can figure out the white balance correction needed (using the histogram) to correct for a particular deepsky filter, then the answer is YES. This correction will however change somewhat with seeing conditions, exposure time and gain setting.