Over the weekend I bought some nylon hosing from Home Depot with a 5/8" outer diameter and a 3/8" inner diameter. This fits perfectly inside the 3/4" tubing, and the 3/8" bolts fit perfectly inside the tubing, so it acts as bushings for the A-Arm pivots. I'll add some bearing greese and I should be good to go.

While in the garage I looked at the month-old frame and noticed that it was already rusting pretty badly. I drove to Ace Hardware, arriving at 8:55. It closed at 9:00. I got some "rust stop" and sandpaper for $5.40. My bank account had $5.68. After getting home again I sanded the frame as well as I could, but it wasn't perfect. After a lot of sanding I gave up on perfection and sprayed the "rust stop" on. It has a nice dark black color to it.