Our Mazda has "manual" control of the automatic where you can tell it to shift by clicking a button or moving the gear selector. But like yours it won't do anything stupid. I've played with a few times, but I just can't get into it.

For towing (or hauling heavy loads in general) - you definitely need to be able to lock out higher gears sometimes in the mountains. If your transmission is hunting between gears, then lock it to a lower one. Our pickup has a tow/haul mode that handles this automatically; the motorhome I had before just had an "overdrive" button that locked out the overdrive gear for the same reason.