MGR. I've cast the stuff before. It's a gawdawful mess. The cast piece may actually come out looking like ca-ca(I refer to this as the "potato-chip" phase) but should "find" it's shape eventually. 'Least that's how it works for me.
I've used the mentioned pancoating no-stick stuff, and even WD-40 (which actually evaporates eventually, therefore, no residue). You can also put some Vaseline in the sun for a while and paint that on, too. Whatever you use, apply LIBERALLY. That foam's first and foremost job is to find its way into any crack or crevice. Especially the one you didn't get release agent into.