If you want, maybe attaching crate the the bottom of your base LR pieces would achieve what you want. I'd be hesitant to use it throughout the sand bed because it seems it might prevent some of the biological action from happening (specifically the CUC from turning over the sand).
sliders, seems more risky than it's worth IMO.
i prefer a finer sand, as do many bottom dwelling creatures (especially wrasses) i prefer shallow, it's hard to get the DSB effects in a DT, so you may as well go shallow and make cleanup easy on yourself.