I would even say this example of an Iwagumi suffers from many critical beginner mistakes. 3 primary stones all on the same plane, still too much negative space, the sides are a bit crowded which draws unnecessary attention to the side panels with the outward facing stones, etc. Yes, you can use minimal hardscape and have an impact, but beginners tend to use too little and undersized pieces for the tanks they are working within, so knowing this...you should try to put more in than you are comfortable with...then remove things if they seem to be too much...work backwards as a way to break the bad tendencies of a beginner. Amano referred to this as the power of removal. Your planting plan sounds fine, obscuring the base of the wood should not be an issue...that piece of the scape will still carry enough weight and will look more natural that way, IMO.