Judy - your blocks are beautiful, and your quilt point on point will no doubt be spectacular.
I did try trapunto, and I found the polyester batting (left side of pic) was best, the cotton batting (right side of pic) left a border around the stitching line, (I used children scissors - blunt end - so you do not accidently cut the stitching line) but the poly batt I just poked in through the back of my block. My husband made me a "poker" out of a wooden chop stick, as you need to tuck it in close to the points - I overstuffed mine, and that really pulled the fabric - I overlaid the block with organza which will really dull your block - I found it was not difficult, just never got back to finishing this one.