Break angle is your big enemy with the stop bar. It’s a long way back, so even with the stop bar sitting on the body, the strings will be coming out a few mm above that. Probably slightly higher than the standard trem, though you’d have to measure it to check. Plus the stop piece looks like it would have to fit further back than the standard trem string bar would sit, again reducing the break angle at the bridge. It’s marginal at best with the standard trem, so any further reduction is asking for trouble.
I’ve never heard of a behind the bridge pickup before. I’ll go and look them up, but I can’t see any point in having a magnetic pickup there. String vibration will be mninal, so very low output, and any notes will be fixed, high pitched and unrelated to what you are playing.