Yeah, the recipe I use calls for 1/2c of navy beans that you mash up before mixing the rest of the dry ingredients together, and the amount of the other ingredients is about the same as yours so I think that would be a good place to start if you want to experiment!
I tend to cook my beans so they have a good bit of structure to them, but next time I make some specifically for this recipe I'll let them get softer. This last batch has some largish bean pieces in it, which isn't terrible, but I'd rather not have them in the future I think.