Durango
- Highway towing only brought milege down 1.5 mpg(non-towing average 16.5) - because towing speed limit in Ca is 55 mph (we run 60 - 5 over). "Sammy" Weight 2100 pounds. Towing without "trailer" brakes (Don't even know if that is possible to rig) Driving speed does make a difference.
Without the Samurai highway mpg range 16.5 - 18.3 (Oregon 55mph limit on highways). There is no "anxiety" producing feeling your towing a heavy vehicle. I have to constantly monitor the rear-view mirror to assure myself that it is still there as it is narrower than the truck.
We call it a "dinghy" too. The place we were camped was about 10 miles distance to the swimming hole. It was nice not to have to break camp to go back and forth.
Speaking of Samurai's. Besides being light they have 4WD (good for desert exploring) and used fairly cheap. Range $2500 - $7,000. Ours is a 2 seater with a large platform behind for coolers, chairs, etc. Some have back seats.
Brian - I don't have a transmission Temp gauge. Something to look into.
KMC -
Vehicles when ordered from the factory are geared for high milege ( 2:0 - 2:20 geared rear differential) if they don't come with a "trailer towing pkg". That package includes a larger radiator, larger transmission cooler, sometimes a larger alternator, and a lower differential gear ratio. designed to produce high torque while lowering top speed (maybe 90 mph instead of 100 mph).
You can check your gear ratio by calling your local Dodge dealer giving him the "VIN" . number and asking for a print=out of the original equipment. You may also be able to Google it. If its low number you can swap the gear out for $600 - $1k if you love the truck. Replace with a 3:73 and you will experience big difference on hills. If you are carrying a load (camper) add an external transmission cooler as the stock one is built into the radiator and does not have enough surface to cool under a big load.
The Tacoma 4 liter V6 , 5-speed automatic and 3:73 rear differential gear provides performance almost equal to my old '77 Chevy crew cab carbureted 454 big block V8 , 3-speed automatic, and 3:73 gearing.
8 mpg towing with Lance Camper and 2500 pound ski boat/ trailer combo . 10 mpg empty (in those days fuel was $1.00 per gallon). We used to say - good news - bad news. Good news truck holds 40 gallons. Bad gets 8 mpg. It was designed to be a "mule" and it was very good at that job.
Times have changed. The current mid-size Tacoma (same footprint as a 1970 Ford F-150) is much more efficient with the computer and fuel injection accounts for performance. ( premium fuel helps motor perform better and get better gas milege - in my case 1 mpg).
Side note: Back in the day we ran regular in our trucks for daily driving. When carrying the camper and towing the boat we ran premium to prevent "knocking" (pre-ignition). Now as an "old guy" for a $3.00 per tank difference I just run premium all the time.