This^
Yes the smaller tires would give you a much better mechanical advantage when towing, both putting the power to the ground and braking.
Look at it this way, stepping back down to 245s would effectively give you the same final ratio as if you kept the 285s you have now and regeared the rearend to 3.90 rather than stock 3.55.
Not to mention, assuming you have narrow stock wheels, the shorter, stiffer sidewall would help with sway rather than the bubbled out 285s.
265s may be a good middle ground though.
If it was a DD/part time tow rig, I would say just weigh the benefits. Looks vs towing ability, but since you said it is a full time tow rig, I would definitely step down to 245s , although the benefits aren't really anything so major that I would buy a new set if the set you had were still good. And keep in mind 245s will be cheaper, and easier to find in load range E.
