Jesus, and I thought I had it bad by having to perform music at my dad's service as a teenager...
I think I feel the same way as you about the bodies. My dad was cremated, as all my immediate family will be, but my grandma was open-casket and while I didn't mind going through the motions and being there for my mom, something about it just didn't sit right with me. Probably the same thing, the spectacle, just like my stupid music, music that I still can't listen to after over a decade. Everything else has healed but that.
I would absolutely skip the next service if I could and remember them on my own time, but there's just no way. Too much responsibility with planning and logistics, too many questions if I'm not there, and I guess I know at this point that I'll be numb enough to get it over with. Takes a while for it to hit me.