My Salvo Rebel had the same issue. I eventually went to a hard goodman but before that I tied the boltsnap to the cord as close to the connecter on the light head as possible when using the soft handle. Ideal? Maybe not. But used it like this for over two years with no issues. The other option as I look at the soft handle sitting here on the bench is to get the dremel, drill, or drill press fired up and make a hole near the edge. Does not have to be big. Just enough for a couple loops of cave line to pass through. Make sure if you do this that you clean the edges up good.
Looking at this pic I'd tie the snap using cave line around the big delrin groove at the back of the light head body. Should work just fine.
Hollis Gear