So, I read a lot about how to deal with poop. And then I tried a few things.
First, I used washed disposable wipes to line the diapers. These actually work very well. And, since my daughter loves to have a wipe with each dirty diaper to just play with, I had some hanging around. I also had a few packages of wipes with only a few wipes left in them that were almost dry, so I just washed these (I use Kirkland wipes from Costco). I put dirty "liners" in the trash* and wet ones went with the diaper into the laundry. I learned to line dry the wipes instead of machine drying to make them last a while. Now I just use them when we aren't home, but I found a more reusable option for day-to-day diapering!
Fleece. I bought a small fleece baby blanket on clearance for $2. I was able to get 19 liners out of it - 13 the length of a prefold and 6 the width. I could probably have cut them shorter, but they work the way they are. Now the my son's poop is more solid, I can just dump the poop off of the fleece into the toilet. It just rolls right off, with barely a trace left. The fleece also works to keep their skin dry, so it serves double duty.
If you have ideas for liners - let me know! I am willing ot try other things out as well.