Regarding what type of trailer to buy, I think your Ranger would struggle significantly harder with a stick built trailer. It should handle a
Scamp or
Casita all right, but a stickie will be taller, wider, and have un-rounded edges... all resulting in much more wind drag at highway speed. And let me tell you, wind resistance is the big factor when you're towing something.
I have had both. With a
Burro (molded fiberglass) I got 14.3 mpg on a long trip through the Rockies. With a KZ
Escape 14RB I got 12.3 mpg on a similar trip. I didn't have a problem towing the
Burro up any long grades, but with the KZ I was making my transmission temperature warning
light come on sometimes even though I was slowing and shifting down. Going up the San Rafael Swell (I-70, Utah) with the KZ in a headwind was not fun, running 38 mph in 2nd gear while cars whizzed by me. With the
Burro I bet I would have been able to stay in 3rd and 10 mph faster.
In general terms, towing is the great equalizer when it comes to fuel economy. Given the same trailer and speed, a big thirsty V8 will get nearly the same mpg as a little V6 or even a 4. I once took the mpg numbers reported on the Scampers' Yahoo group and IIRC the average difference between the 4's and the 8's was less than 3 mpg, with the 6's about halfway in between. I would guess that @ 60 mph you should get about 15 mpg with a FG trailer, whereas a larger vehicle with V8 might get you 14... not much difference.
My opinion: you can tow a FG 'egg' with your Ranger, but if you want some other travel trailer you'd better shop for a bigger truck.