Question on welding in new trunk panels Options

[moparrob]

Thanks in advance to those of you with superior welding skills.

By way of brief history, I have a six-cylinder conversion with front mounted oil cooler and Puller fans. I'm going to build sheet metal ducting to exhaust the hot air out through the bottom of the trunk.

I have already mounted the fans and the cooler and in the process of determining how to exhaust the hot air.

I purchased two louvered panels with the intention of cutting out a section of my front trunk and installing these panels to help exhaust the hot air coming off the front oil cooler. I know there are several different methods to attach these including lap welding and butt welding but I'm not sure the best way to do this for a good finish on the sheet metal and the welds. I want to avoid water getting trapped and rusting the trunk floor.

Here are some pictures of the trunk and the new panels:

(IMG:http://www.914world.com/bbs2/uploads_offsite/i954.photobucket.com-11663-1340506614.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i954.photobucket.com-11663-1340506614.2.jpg)

I'm sure a butt weld with stitch welds around the perimeter would certainly seal it but I wonder how nicely the underside would look and how hard it would be to finish the underside.

I have a flanging tool so I could create a slight flange on the louvered panels and cut the opening slightly smaller than the louvered panels so they could set on the step.

I suppose I could also plug weld them and use seam sealer on the inside. I just wonder how well this would waterproof the bottom side.

I also bought some weld through primer which I have never used. if I decide to plug weld would this be a good opportunity to use this? If so, any clues on the best way to apply this product?

Again, I appreciate any input on this since my welding skills are very novice at best. Thanks guys.