  Santos' construction of counter-examples to the Hirsch Conjecture (2012) is
based on the existence of prismatoids of dimension d of width greater than d.
Santos, Stephen and Thomas (2012) have shown that this cannot occur in $d \le
4$. Motivated by this we here study the width of 5-dimensional prismatoids,
obtaining the following results:
  - There are 5-prismatoids of width six with only 25 vertices, versus the 48
vertices in Santos' original construction. This leads to non-Hirsch polytopes
of dimension 20, rather than the original dimension 43.
  - There are 5-prismatoids with $n$ vertices and width $\Omega(\sqrt{n})$ for
arbitrarily large $n$. Hence, the width of 5-prismatoids is unbounded.
