polyisocyanurate

the foamie bug has bitten me again & a new and different build is about to begin.
my brother has a full sized dodge pickup truck & i am going to build a campable, popup, foamie, fastback cap for it.
their is one issue. it's going to be painted black to match the truck, and he has been known to camp in the desert southwest.
my old testing showed that extruded polystyrene begins to shrivel and delaminate under these conditions.
my solution is to use the yellow polyisocyanurate instead.
test samples with glass and 5 minute epoxy show similar strenth to the pink or blue stuff & it doesnt start to collapse until about 400 degrees (i tested it in the oven next to some pink stuff).
my 2 questions are: has anyone ever built with this? and: is it compatible with vinylester resin?
the vinylester should save me quite a bit of money if it's compatable.
i eagerly await educated opinions from those who have built more than i.

my brother has a full sized dodge pickup truck & i am going to build a campable, popup, foamie, fastback cap for it.
their is one issue. it's going to be painted black to match the truck, and he has been known to camp in the desert southwest.
my old testing showed that extruded polystyrene begins to shrivel and delaminate under these conditions.
my solution is to use the yellow polyisocyanurate instead.
test samples with glass and 5 minute epoxy show similar strenth to the pink or blue stuff & it doesnt start to collapse until about 400 degrees (i tested it in the oven next to some pink stuff).
my 2 questions are: has anyone ever built with this? and: is it compatible with vinylester resin?
the vinylester should save me quite a bit of money if it's compatable.
i eagerly await educated opinions from those who have built more than i.
