This is a great shot. I think I have found a new target when my camera gets back. I probably know the answer to this question, but could I get a similar results with my f/4.9 and a 2x barlow? I know barlows are usually frowned upon unless it is for planetary or lunar, so I am guessing no.
There are a ton of other variables that might affect your ultimate results, such as how dark your skies are, and the fact that my shot was done with an 11 inch scope and you would be using an 8 inch scope.
But if your sub exposures are long enough to get you up out of the readout noise of the camera, using a good-quality 2-inch Barlow in this instance to get you to f/10 should be ok.
Just be careful because depending on the spacing, a nominally marked 2x Barlow can be a lot more magnification than 2x because the sensor in the camera is a lot further away from the Barlow elements than an eyepiece, so you might end up working at f/15 or f/20 instead of f/10, and then your exposures would get extremely long.
But give it a try!