Weight the truck first. Put the whole family in and all the stuff you normally carry, full tank and have it weighted. My registration said my truck weighted 4,000lbs (got it used and with commercial plates). I went by that for a long time, then I weighted it and found out it really weights 5,000lbs (5,300lbs with the shell). Weight it and go from there. Steeper gears in the real whould also be a big help in towing if you can live with them when not towing.