I think I like the concept here. By partially burying the DW, it will not only anchor it down until it gets saturated enough to stay sunk, but it will also make the scape look more natural. Further, it will also reduce the chance of it looking overbearing for the nano tank. Only thing to be cautious for is proper plant selection and placement. Otherwise, the DW would just get covered up and be a waste of space, making it a little difficult to work around when performing tank maintenance.