There are a of of ways to look at potential problems you may have and a lot of ways to deal with those problems. A sand bed over three inches deep, if made up of sugar fine sand, would make up for the use of small amounts of live rock, as you really are not all that short of rock when your intent is chiefly to house large fish. Fish will put up with water with much more organic nutrients in it than coral and other invertebrates will. A deep sand bed is a good bio system in and of itself. A lot of commercial frag tank systems use no live rock but use deep sand beds in large refugiums with algae and corals as nutrient exporters instead. A second skimmer would be an excellent choice for a tank with chiefly large fish. And then your live rock and sand bed would have much less organics to deal with allowing you the openness that large fish need. Your problem will be in if you decide to use more sand and therefore use the sand bed for a biological filter, you will need to stock your tank gradually (one large fish at a time or a couple of small ones) instead of in large spurts (3 or 4 fish at a time). This gradual method would also apply if you used base rock for the rest of your rock. This need to do things gradual is to give bacteria the time to colonize the new rock or sand to some appreciable extent. A second skimmer would allow faster stocking of your tank. Bio balls are not bad in a fish only or a fish only with live rock tank. However if you plan on keeping corals or invertebrates bio ball filtration is not a good idea.
