I had a great day today, and got a lot done on the trailer. I got the new 3500-lb. trailer axle installed, and started on the receiver tongue bracket set-up.
For the axle install, I used the original square U-bolts that straddle the leaf springs. This required a couple sets of spring perches. The only things left to do are making some lower shock mounts (the original mounts were welded to the spring plates, which are actually welded to the A3 axle). I also have to get some bump stops, as I had to remove and cut down/section the original mounts because the U-bolts are now closer together than the original ones. See detail pic below, and you can see the brackets on top of the springs. The trailer now has the same wheels & tires as my Jeep LJ. The axle width worked out very nicely (62" axle width with 2" wheel spacers, for a total width of 66"). The tires are just about even with the fenderwell openings now.
I also ended up picking up an Adventure Trailers tongue bracket rather than scratch-building one. I had to trim about 1/2" off each side in the back, and a couple inches off the tongue of the trailer for it to work (very straightforward). I still have to trim the top plate to match the angle of the A-frame tongue. I also have to decide if I'm going to go with the stock tongue length (which gives a 100.3" receiver-to-spindle length), of if I'll keep the extra length with the 18" receiver, which would add about 4" to this length.
So, it's coming along nicely, and it won't be long before I'll have it ready to roll.
Craig