am I taking a serious risk by making this drive without one?
This may be the only time I tow with this truck. Also, just to be clear, running the OD OFF will help keep the temps down?
You are not taking a serious risk. Go with what you got.
Millions of vehicles are set up the same way.
There is a temp indicator if it gets too hot.
OD off will keep the temps down if the transmission goes back and forth too much between 3rd and 4th with it on.
It's the torque converter not locking up that causes the heat build up.
If it locks up with OD on then fine.