At 100km/h (62mph) the auto will be spinning the diesel at about 3600 rpm.
The spec for the 1.6 is 71lb/ft at 2500rpm, and 52hp at 4800rpm.  That's a
much higher redline than the 1.9TDI at 4000rpm.  So the 1.9 is likely out
with an AT unless you never drive on the highway.  The 1.6 could hang in
there, but I think the problem is in the powerband.

At 100kmh the 1.6 is probably maxing out at about 50hp.  Torque drops from
its max of 71 lb/ft at 2500rpm.  Factor in the power lost through the
torque converter, and you have a very very slow van.  If I recall correctly
most of that 50hp will be overcoming wind resistance leaving little for
hills or headwinds.  Forget about going uphill with a loaded van :-)