They're not going to be able to weld that hole 100% without using some type of filler.... unless modern body shops have some tricks my dad didn't know (which, they are constantly coming up with new tricks and technology). Maybe leading it in.... but I really don't see any way of going about this without using a filler of SOME type. If you don't use bondo properly, if you don't prime it to seal it and then paint it, yeah, it can accelerate rusting, yeah, it could draw up. But if you do it right, it will not. This is why after you bondo, you ALWAYS atleast prime it afterwords to stop these said things from happening. I don't think something so small as a bolt hole in a trunk needs to be welded.... but if you're more comfortable and sleep better at night, go ahead and spend the money and have it welded... but still, there's going to be a little bit of bondo, I'm about 99% certain that some type of filler will have to be used to make the welding smooth.

 

kinda off topic:

The other day I saw a mc with a huge looking nascar/"duckbill" style spoiler that had to be aftermarket. It wasn't straight across like the factory spoliers. It had a hump in the middle that seemed to fit the curvature of the trunk more. Anyone see this style before?


edit: nevermind. did a quick google search and seen it in a ground effects kit.

 

Yeah they would probably have to use a skim coat of filler glaze over where they welded. Body shops dont use lead anymore. Thats old school, there are fillers out there with much better bonding and rust inhibiting properties. Its not so much a matter of corrosion with filling the holes with bondo if you seal it and paint it on both sides. The problem is that the bondo only adheres to the metal, it doesnt become part of the metal like a weld does and doesnt offer the same integrity that a weld does. Over time of you opening and closing the decklid, the bondo in the hole WILL work itself looks and possibly crack and fall out in the future. Especially since bondo shrinks when it dries and doesnt fill the hole quite as tight as you pack it in when its still wet. Not to sound like a know-it-all, but I do body work for a living. I work with these materials every day and Ive seen it happen countless times.