The weight up high does make a difference. As far as removal goes, I was ready to cut the roof skin from a non-sunroof Rabbit and tack it over the hole, but a good mechanic I know suggested using the removable sunroof panel itself, and some round bar stock to fill the gaps where the sunroof seal would normally be.
It took some time bending the stock around the sunroof panel, and grinding it to fit snug, but then the roof it will fit flush, and some bondo will fill in the gaps.
When welding, take your time, as the roof can warp with heat.
PJ
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83 Rabbit GTI - future ITB