Third time is a charm!! I lowered another one today, and it's even better than the first two! (I can do it start to finish in about 5 hours now, by myself.)
The other two are lowered 2-1/2", and the second one I did I also slid the axle forward 1/2", which worked out well. (More shock length, and still looks centered in the wheel opening.)
Today I cut my 2-1/2" square tube lengthwise down the middle, so I got two U-shaped pieces that were each only about 1-1/8" tall after I cleaned them up. I pointed the legs up, against the frame. It was a little tricky to get the bolts tight, but I managed. So this trailer is now lowered 3-7/8", and I LIKE it!! I also slid the axle forward 3/4" to add some shock length.
I had considered just letting the axle rest right against the bottom of the frame, but I don't think it'll work unless I leave off the shocks. Plus, this trailer looks pretty low now. I don't think I want it any lower.
One thing I did notice in doing all these trailers is that my two 2009 trailers have shocks that won't collapse the final inch of shaft into the body. The older trailer has shocks that do collapse completely. The fully collapsible shocks will work better on lowered trailers. I probably should move the fully collapsing shocks to the first trailer I did, since it's shocks only have 1/2" or so travel before they bottom. (I put zip ties on them and they don't even move 1/2" with me really shaking it around... even with 2000lbs of water, pump, and hose reel!)
I'll try to get a few pictures up tomorrow.