Welding frame - can i get some advice?

[Longstep70]

So I'm practicing welding frame material on a couple of stubs cut off from another frame i had lying around - around 1/8" thick i guess. I'm using my Miller 180 and .035 wire.
I started with the factory settings for speed and current on 1/8" steel - 4.5/50. I was trying to nail down my settings for full penetration. The first couple of tacks I tried i wasn't getting the weld all the way through. I started playing with the settings and the gap between the two pieces. Increasing both numbers helped but I was getting a *lot* of heat and a lot of material in the bead very quickly so i backed off the current and tried to bump the wire feed to try and increase penetration without building up a large bead on top. I got mixed results and I have a few pics. Can I get a little advice from the more experienced of the welders on here?
Here's my first couple of tacks showing the weld pieces and the gap I was trying:
http://i6.photobucket.com/albums/y23...e/IMG_3423.jpg
and here's the back of the same 2 tacks:
http://i6.photobucket.com/albums/y23...e/IMG_3424.jpg
Here is a later pair after tried running a couple of small beads. i know they don't look great but bear with me..
http://i6.photobucket.com/albums/y23...e/IMG_3427.jpg
and again from the back:
http://i6.photobucket.com/albums/y23...e/IMG_3428.jpg

By the end of this sequence I had nudged up the settings on the MIG to 5/60 and I still don't feel like I'm getting proper penetration even with a chamfer on the edges. How should I proceed here?
thanks

-Andy