re: Trench-digging heatshields
I recall hearing that that side of the crater appears to have more rocks, which likely would slow things down. If there is really the prospect for a long term mission - 6+ months - maybe they would try it. But going around to the impact point would add 600-800 m (?) to the traverse.
Also, I suppose that I am a little bit surprised that the heat shield landed with a couple of hundred meters. I had assumed that it would have landed kilometers away.