I have a Thule rack on my '89 Syncro (<--req'd VW content) and I'd like
to keep an extra 5 gallons on my rooftop carrier, preferably in one of
those well-sealed plastic gas cans.  However, the carrier is an
*enclosed* - though not nearly airtight - shiny black fiberglass cargo
box.

Would taking this setup down to Baja on our upcoming Syncro Safari (<--
gratuitous VW content) turn my cool new Thule carrier into the FLAMING
ROOFRACK FROM HELL?  How hot does it have to get in there to turn a
standard approved legal gas can into a napalm bomb?

Nomex suit ON,
-Steve