As a veteran of a LOT of towing, how the manufacturers arrive at
their advertised capacities is a bit bewildering. That being said,
the Astro-Van should be able to perform the "emergency" job, as
described. Definitely DO NOT tow w/ front wheels on ground,
and DO remove the driveshaft. In which case, something to seal
the tailshaft (so that you don't leave a trail of tr-fluid all the way
home) would be a good idea. At one point, cheap plastic units were
available. Otherwise, junk-yard another yoke. And something to
lash it in place (wire, string, tie-wraps) should also be in the tool-box.
(Get a good running start at the hill

)
Good luck