Hello Rog! Everyone has giving you some good stuff to chew on. Here's my 2 cents: First, most rv rigs, be it a tt, 5'er, or mh get about 7-10 mpg when cruising on the highway. The weight differences in rigs has less to do with mpg than does WIND RESISTANCE. Any conventional trailer or mh will catch a lot of wind, and the faster you drive the worse it is. The point is, don't get too caught up in weight as far as mpg. Just be sure your trailer, loaded for travel isn't too heavy for the truck. Most of us grizled old rvers consider the trailer loaded up shouldn't weigh more than 70 to 80 % of your truck tow rating, and remember that a lot of weight in the truck will take away from your tow capacity. If you get the f150 do get the 5.4 engine, just so much better for towing even if you get a really lite trailer. Now, I think its about impossible to have a good duel purpose tv these days if you are concerned about gas costs, just my opinion. I was using my 5.4 expedition to tow our 30 ft Trail-Lite (4760lbs dry). It was my dual purpose ride. Anything dual purpose is a compomise, pretty good at both towing or not, but not too great at the towing part or the commuting part. So, I recently made a big change. I studied this for months. I love our trail-Lite so its staying. By the way, I got 8.5 to 9.5 mpg towing from Texas to the fort. I hated stopping every 3 hours or so for gas, a 27-30 gal tank don't go far when towing! So, I recently bought a super nice, 2000 Excursion, V-10, big towing mirrors, a one owner, only 78,000 miles. It has a 44 gal tank so instead of 5 gas stops, now I can do our 1035 mile trip easy with 3 gas stops. Plus, the Excursion is a great tv, 10,000 lb tow cap. with my 3.73 gears. I go to a Ford enthusiast board and learned a lot. I expect to get about the same mpg as before, maybe even a little better, cause now i can use overdrive on I 10 thanks to the Super Duty trans and chassis. Plus it has a lot more room in the back, almost 2 feet more than the expedition. With 4 adults, a baby, 2 Siberian Huskies and a dashhound, we need the room. Now I have a wonderfull tv with a long range gas tank and heavyduty trans and lots of room. No compromise here. I am selling the expedition, then i will buy an older 4 cyl car for my daily driver. No compromise here either. I am looking at a Honda Accord, about a 96-98 with low mileage for around $4000. I only paid 10,000 for my Ex. I will be happy to occasionally drive it when I need it, but mostly keep it parked, saving gas and wear and tear, keeping it in its current like new condition. I am very very sure that for myself, I am doing the right thing. You know the accords are legendary for reliability and long life, and great mpg. Also, word is, the V-10 may be the best big engine Ford ever made. Guys are driving them 150,000 , 200,000 miles and more with normal maintenace. I did look long and hard at the 2000 to 2002 Ex with the 7.3 psd. It is a fine engine for towing, decent power, great mpg, very strong and reliable. I just couldn't afford it. The same Ex I bought would have been around $18,000 with the 7.3psd. My v-10 is silky smooth, powerfull, and I actually got 17 mpg on the 325 mile trip home when i bought it! Thank you autotrader. Now, know this, I have the trailer for the wife. I would have been very happy in a nice popup. We used to tent camp when we were young and loved it. But my wife wanted a big trailer, like a 36 ft 5'er, so we did compromise and got the Trail-lite 8306S. We chose not to get bunks because they tend to take away from living space. To get bunks, a Queen bed, and a spacious living area, you are getting a very big trailer, and thats just not for me. I will close by saying the only way to get good gas milage is to get a popup or a Hi-Lo (hard sided, top drops hydrolically). I kind of wish I had a Hi-Lo, probably getting about 13mpg . That would cut my vacation gas bill by 30% and extend my range by 30%. Then I could easily drive from east texas to the Fort with only 2 gas stops. I enjoy stopping at the big rest areas, but hate the gas stops! Of course I would also use my cabin tent, guys and dogs in the tent (fun camping), girls and baby in the Hi-Lo. So I guess I would change but my wife would beat me up over it. I think she would like the Hi-Lo if she would try it. They do have a full bathroom and everthing. They are very expensive new, I would get a used one in my budget. Dang, my 2 cents became a 2 bits, I hope my rambling makes sense.