Ok - so I haven't read this whole thread but is there a reason for not using the vertical foam strip method?

Forget about the heat gun stuff- just make a heat box with a fan heater ($20) or heat lamps and some ply.
Slide foam in for 2 or 3 mins pull out and bend into place then pull out the next bit of foam.
Lots of Farrier Tri builders use this method with great success.
If this is no good - have I missed something?

Regards,
Phill

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!