[a/s] Towing capacity

[Peter E Kaiser <pkaiser@xxxxxxxxxxx>]

I have a 1993 Ford Explorer with a 4.0 Liter EFI V-6 engine, 4WD and
automatic transmission.  There is a 1964 AIRSTREAM 20' Safari for sale
that just may be that starter trailer I want.  It weighs about 4000
pounds.  Now the question of towing capacity has come up.
Here are the specs from the door on my truck:

GVWR:  5280
Front:   2540 LB
Rear:   3000 LB
Transmission:  T
Axle:   41
Springs:  NU
Type GVM  U34V

Using the manual, I find that the trailer weight is rated at 3200
pounds—I think this is for the bumper hitch.  If I were to install a
class III hitch under the vehicle and use a weight distribution system
what would my capacity be?
Does anyone on the list have a similar vehicle or know how I can resolve
this question?
Thank you,
Peter E Kaiser