Protonmadman

Hey everybody, this is my first post here on TU, and I hope i'm not regurgitating past topics here but... I just cast my first resin glide bait, a 8.5" rainbow trout. My first casting was as a single-piece, but I decided to lay the molds out flat and try it in two pieces. The reason for this was to try and cut weight by hollowing out the front and rear sections when it had cured (which I did), then epoxy everything together. The result is still 7.5 ounces, as pictured. So, my question is: Is it possible to cut this weight of something like this down to, say, 4.5 or 5 ounces? Is there a technique/resin type that can help cut the weight down? I'm using a two-piece silicone mold based upon a hand carved wood trout design I made. Any suggestions would be much appreciated!