The skin of our fivers is actually made of gelcoated filon unless they've changed process in the last few years. Unless you have previous fiberglass body repair experience and the equipment to assist in the repair ... I'd suggest just bite the bullet and have it done by professionals. After the base fill on the gouge ... assuming you have the gun to do it with ... Gelcoat is very difficult to spray on uniformly in a horizontal position let alone vertical. Then there's color match (there are many shades of white then factor in UV exposure), many stages of wet sanding, stages of compounding and buffing. When you talk of high gloss gelcoat, I'm assuming your unit is fairly new ... it would be a shame to end up with an even more embarrassing spot repair that someone else is going to have to start all over with (read extra $$$$) to make it look like anything. If it's an insurance issue ... use money set aside for rainy days. If looks is not an issue and you just want it filled ... Google fiberglass repair and go from there.
