Towing and Transmission

I bought a 2002 Ford Escape specifically to tow my
belongings across the country. The day before I left,
I got an oil change and had all my fluids topped off.
When I left, after I stopped for gas, it started jerking
and the O/D light started flashing. I pulled over to
check it out. It would no longer drive after that.
Apparently my transmission fluid was "bone dry"
and the whole thing had to be replaced.

I am towing a 5x8 trailer and the only things in it are
a motor scooter (not more than 200 pounds) and
some boxes of clothing, but the mechanic told me
that all the extra weight caused the seals to melt
and all the transmission fluid leaked out.

I am only about 1/5 of the way through my trip.
What do I do to keep this from happening again
once the transmission is replaced?