filling the roof channels

[markl at hiwaay.net (Mark Langford)]

I'm about to paint my 87 Scirocco, and spent Friday removing everything
that's not a faded-to-pink version of Tornado red.  After peeling off the
black "drip rails" from the roof (that's all I can think they'd be for),  I
called the VW stealership, where I was told these were available only if you
bought the entire roof.  Well, I'd already been thinking of getting rid of
them anyway, so that confirmed it.

I was thinking of mixing up some epoxy with microballoons and filling them
completely with this stuff (same stuff composite aircraft builders use), as
it's not as prone to cracking as polyester type body fillers.  Has anybody
filled these channels with something, and did it last without eventually
cracking? And what did you use?

Thanks a lot,

Mark Langford, markl "at"  hiwaay.net
1974 2110cc Karmann Ghia  (http://home.hiwaay.net/~langford/ghia2.jpg)
1987 2.0L 16V Scirocco
1999 1.8T Audi A4 Avant
2001 1.8T GTI w/APR chip
see Corvair powered KR2S project at http://home.hiwaay.net/~langford