Body help/advice needed

I had the day off today so I thought I would tackle the inner fender wells. I cut 1" wide by 8" long strips of body metal. then bent them in half so I ended up with 90* angles to to make the inner fender lip. Bunt them to fit the contour and welded them together. Then I cut patches to fill the side areas and welded them to the new lips. But then the problem started as I am struggling with the welding of the new metal to the old inner fender. The old metal is to thin it burns thru to easy. Ive tried .023, .030 and .035 thick wire. I have a hobart 140 and I have it set at the lowest setting and wire speed down to 30. Not sure what will make this easier. The metal isnt rusty its just so thin. What do you do to getaway from this?
Thanks
Rod