Ed, I usually use 1/8". That gives me pleanty of material to grind to match door gaps. You could use the 3/32" if you arent far off. I always weld outside solid and the inside on the opening end of the doors. If it's really hidden i might just stich on the inside, 1" skip 1" and weld 1".
There have been times, (like somebody didn't weld qtr panel replacement on correctly) that i've added there. When i do this I generaley weld outside solid and stitch inside, grind level and skim filler to dress it out.