Assume the screws are nicely fixed; then major flexing can occur only on the long axis. Components that are mounted along this length shall experience the greatest stress.
I presume that components mounted along the length (long axis parallel to the length of the board) are most likely to suffer cracking.
Near the edges, there is some relief (temp will be highest in the centre) and out of all the components mounted longitudinally, G will see the largest stress.
But because of its size, this is also most securely fastened.