I guess I would try one of the following options:
1. Create two separate widgets. The first one is filtering just the latest blogpost (by setting the maximum to one and order descending. The second widget should render all the blogposts and with JS or CSS you could hide the first one (the newest blogpost)
2. Create one new widget that acts like a template for the blogpost list. In this template (which is a UserControl) you could manipulate the data on databinding. I've done something similar with the News widget. Here's my code as Gist (since I cannot add code through this editor)
Hope that helps a bit?