how much space is there from the top of the heater to your van roof?there should be at least a 2 ft clearance.mine is a bit more than that.no problems.
I've got the same thing poleman.Been meaning to get round to it for ages.If you can't get the proper shield, you could always get a bit of sheet aluminium and fashion one.I think I've got some in the garage.If I've got enough to send you a bit I will.