I haven't heard the tip about heating before painting. Is that using VHT, or was that with BBQ paint? In the past, I've not been pleased with VHT, it just didn't hold up, but RustOleum BBQ paint has held up well for me. I just put on enough paint to cover them, trying to avoid any "build" of paint like one would normally do with rattle can paint. If it doesn't work on these I'll admit you warned me.
Lynn