I went to Walmart over the weekend and picked up some car ramps. Pretty nice, some sort of a composite material, heavy duty (12,000 pound capacity) fairly light weight and they won't rust. I tried them out yesterday, and it seems like it will be a pretty good option over the old wood platform I had.
Here are some photos of the ATVs on the trailer. First time I have had both of the new ones loaded up at the same time.