mmmmm, think a gas torch would be too fierce a heat Paul,
ok, another bonkers idea to try
send the missus out for the day with the credit card (she'll be out for ages)
fill an old chip pan with oil-put it on the barbie til its hot, cooking oil will reach about 300°C and will give a nice uniform heat, transfer to the bondage device in the vice, spray the cap with your freeze spray - et viola
film these events for you-tube-it could be a classic !