I have a 96 Toyota Tacoma, 4 cylinder truck with a shell on it. On the open flats I could cruise at 65 - 75 mph if I felt it safe, depending on the speed limit. Az has a 75 mph limit with trailers. The hills were a different story. I used 4th gear a lot and once I had to go down to 3rd gear. In 4th I can go anywhere from 50 - 65 mph and in 3rd I can go up to 50 mph and hold it there up a steep hill. In short, a 4 cylinder Toyota truck just barley has enough power to be comfortable. Any less power and it would be too much of a load to pull.
As far as how the trailer handles; It did not seem to make the truck act oddly or really any different than driving without a trailer. I was cautious on curves after seeing those photos of eggs that flipped on their sides. It was a cake walk for the most part. But this was nice sunny and warm driving for me. No rain and certainly no ice or snow. My trailer has electric brakes
but any good size vehicle could get by without the brakes
in dry conditions. With the brakes
my truck stopped like there was no trailer on it.