Do you think the Forsythia plants would live through the winter if just laid out like you said, in neat rows and then covered the roots with a heavy layer of leaf mulch?

It depends on our winter. Sometimes it can get below zero here and then I think it would kill them. But if I wrap them up and sort of bury them in compost (which is like dirt), then they might be ok. If we get a mild winter, just leaf mulch might work but we never know...last winter 2015-16 we had no winter at all, but the previous 2014-15 was brutally cold.