Larry
I agree totally with what you said about towing is not a great idea but since a lot of us do it this is what I have discovered since I got my first 700R4 in 1985.
I have had three different vehicles with 700R4s that I have towed trailers with there are two rules for making them last. 1 install a huge trans cooler and a transmission heat gauge. If you are towing in OD and heat guage starts to climb down shift. 2 If you hear the convertor start locking and unlocking down shift. I have pulled many a mile in OD by using these rules. Also if you are going to pull with a OD transmission you should have at least a 3.73 rear gear. People forget that a 3.08 rear gear be comes a 2.10 in OD while a 4.10 becomes a 2.80 in OD. I only had to toast one transmisssion to learn the above, since then I have never had a failure.
HEAT KILLS AUTOMATIC TRANSMISSIONS WITHOUT A DOUBT.