All you need to do tri colour imaging is the DMK21 and a filter wheel or slider with your LRGB filters. Or if you want an OSC (one shot colour) camera, get yourself a DBK21...they're $50 cheaper, from Bintel...
https://www.bintelshop.com.au/welcome.htm
BTW...don't you mean your 8" dob is on an alt/az mount??. If it's on an GEM of some sort, then you'll be able to take guided shots with your camera and the mono camera with filters etc, will be your first choice.