Mojo,
Unless you really work on minimizing wasted space (and thus volume) you will be doing well to get 2-3 molds per lb of RTV. By using the above process or the earlier mother mold process, you can trim the RTV mold before making the liquid plastic cast of it to reduce the volume. Basically, once you have the RTV copy, you can cut around the legs, claws, areas in between cavities, etc. Your mold won't be pretty and square edged, but you will still have RTV in the pot and $$$ in your wallet.
Have not worked with the LMR. Suppose the effectiveness depends on what you try to make it do. Looking at your post...you could use the LMR for 2 things: 1) make the initial mold from your sculpey original, then use resin to cast a "reverse" mold in the LMR, and follow the above process to duplicate and produce your molds 2) if using a resin mold you already have, use the LMR in place of the soft plastic in the process above.
I've been using the RTV for LC...10# kits. Have tried a few others, from non-lure sources with so-so results. Better to pay a bit more and be happy with the end result.