Newbie looking at purchase and vehicles

As you said, while towing your mpg will be low. Anywhere from 10 - 15 mpg. One consideration for a tow vehicle is size of gas tank. Most any small truck Tacoma, frontier, ranger etc. will pull the 178 with plenty to spare. I think the mileage is all the same-ish between them. Probably get around 20 mpg avg not towing. 

+1 to StephenH. 5000 lbs min tow rating/500 hitch rating for that trailer.

Ignore the trailer empty weight spec, it is meaningless. My 179 has a stated empty weight of around 2700 but in reality weighs about 3700 loaded, with 500 on the tongue. Use the max gross weight of the trailer instead, you will be closer to that than to the empty weight, and about 13% of that should be on the tongue. Why 13%? Minimum is 10% and recommended range is 10-15%. But the hitch load varies depending on your loading and how much water is in which tank, so 13% is a nice midpoint.

The tow vehicle ratings assume only a driver and no passengers or cargo are in the vehicle. Of course that is far from reality. And then you have to ask yourself how close to the manufacturer’s limits you want to be operating on a daily basis.

If you plan on boon docking you might want to go a bit higher still. You will be carrying water, dual batteries, a second propane cylinder, a generator possibly, more gear. We boondock almost exclusively and my 5000 lb rated Highlander still has some headroom on trailer weight, none on hitch weight, and we pack light and only take the necessities. No kayaks, bicycles, big grills, tents, picnic tables, extra passengers, etc.

SUV vs pickup is a personal choice based on what else you want to do with the vehicle. Either can work for you. Diesel vs gasoline is the same. Don’t get diesel because of the better mpg. Its a different fuel so that’s a false comparison. Diesel is a heavier hydrocarbon which higher energy content per gallon, and costs more per gallon too. As StephenH points out, around a 29 gal fuel tank is needed. You will wind up around 13-14 mpg towing at 60 mph on flat ground with no wind, regardless of what you tow with, everybody does. It’s the air drag from that big box, so the only way to improve that is to slow down (or wait for a tail wind).

Finally, unless you get a tow vehicle with a high hitch rating, say around 700 lbs or more, plan on getting a weight distribution hitch to put some of that hitch weight back only the tow vehicle front axle.

thanks eveyone for your thoughts/ideas and input, very much appreciated. I'm kinda surprised by the not so good gas mileage when these trailers are much lighter than the older ones. I remember our older 20 foot Kit trailer from the 90's with our full size Chev pickup got about the same gas mileage as what was said here from folks here and other forums. Maybe we need to go back to tent camping LOL...

Among the good choices in the mid-size trucks and SUVs, you should also consider your local dealers, warranties, etc. If you settle on SUV-XYZ, but the nearest dealership for that brand is 150 miles away, it might be worth looking at SUV-ABC because you can get one for not much more money and only have a 20 minute drive to the dealership. 

hi Rick, now that's exactly the information we're looking for...thank you. We are looking at the Colorado and see that the 3.6 Litter has a tow weight of 7500.