I don't think you can rig that up after the SSR and get the results you want. Something in how SSR's work their magic.
When I was testing my setup with a multimeter it always showed a constant 120v per lead, even the SSR lead (240v system), whether the built in SSR light was on or not, and whether or not the power should be flowing or not.
I wired my "element is on!" light to my switch that turns on the juice to the SSR, so while it doesn't truly show if the SSR is firing, it shows that it SHOULD be, and I can look at my element for bubbles.