Mike,
Be nice if you had some pictures of the problem area.
What's your DIY skill level like? Have you done any body repair work using fibreglass and polyester resin body filler? And can you use a spray gun or cans of aerosol paint?
I'm assuming that the high top is rigidly bonded, not a flexible joint, onto the Traffic's bodywork? And that it's a lap joint with a visible edge?
My suggestion would be to make a smooth edge to the lap joint with some flexible body filler, then a fair amount of sanding so that you have a reasonable smooth curve from van roof into the high top.
Then prime and paint that area - unless you've used a spray gun before you won't get a good match - but you could hide it as follows: If your van has coloured artwork or areas of contrasting paint, then run a band of the contrasting paint around that section of the roof, and / or apply a wide decal to cover the join.
Robert
