A friend and I had a play with some light rope and a hocky mask

Had my 40D tripod mounted and wanted to use rear/2nd curtain sync. The wireless flash triggers I have don’t support rear curtain sync so I put a small flash trigger sensor onto my Nikon SB-28, set it to 1/2 power and placed it on a light stand. I then put my Camera mounted Canon 550ex into rear curtain mode and had it pointing away from my subject, but so the sensor on the SB-28 could see it fireing. The 550ex then triggered the SB-28, effectively giving me off camera rear curtain sync.