Unfortunately there is not a good way to avoid Atl and going I-40 is 100 miles further and not all that good. I go through downtown often (yes with the MH & toad), but on I-75 and just not at rush hour. After Ga Tech (I-75 & 85 are together) you loose the two right lanes (exits) and then the two right lanes are the ones for I-20. I use the HOV lane but you have to be willing to put the pedal to the metal and I'm not sure if there is a I-20W exit from the HOV lane south bound. I would just not be in the right lane and when it disappears move left one lane when possible. Yes you are bigger and the blinker plus hugging the left line usually works. Also once inside of I-285 there are very few 18 wheeler's as they are required to use I-285 unless delivering in downtown Atl.