[bestclimb]

How much would you be using the tow vehicle without and without the load? If it will primarily be used without the load then the Highest FE vehicle that is capable(as in is rated for) of pulling the load seems the best option. If you will only be using it with the load then pick a vehicle that will get good mileage loaded and have a decent margin over that.

When talking about 3500 lbs I don't know of many cars that are rated that high. Think very hard if you are incline to over load. Sure the car may do it (and may be rated for it in other markets). Consider that if you are over the limit for your vehicle and you get in an accident (even if it's not your fault) you will be liable as the load you were pulling was not legal, the manufacture certified their product for a certain weight, you are on your own if you care to exceed it. Then try asking your insurance if they would cover you over loaded.

Stopping ability trumps Mileage. It don't matter how much money you save on fuel if you bend someone else's metal or damage flesh it ain't worth it. It does not matter how much Insurance you have it can not give back their time or take the pain you caused them away.