Put the axle together today, I ended up going with 1 3/4” .120 wal hrew over 1 1/2” .120 wall dom, just wanted to get the outer diameter of the axle tube up to 1 3/4” for the spring perch’s, should be good for 1500 lbs or so now.
I have all the steel ordered, using 2x3 .088 wall for the frame...