I suspect you are right about a sheet that would help eliminate handshock designs. My first selfbow was parallel to half way up the limb. I tillered it just like the first couple of laminated bows I had made with limbs tapering from fades to tips. It wasn't pleasant to shoot. I didn't even know what handshock was at the time.
Luckily I had just discovered PA and posted pictures. Marc told me to take a little more wood off at midlimb. The bow was a pleasure to shoot after that. I learned two lessons from that. One was elliptical tiller on parallel limbs and the other was to be greatfull when guys are critical of your tiller. That was the first thing Marc taught me, but not the last.
Justin