I'll vote for the Round-Up. That was late 50's, I'm guessing 56-57.
First Paratrooper I saw was trailer mounted , in 1960, I think.
Centers of a number of rides were trailer mounted, at least on some shows, Herschell Rocket, Herschell Twister in addition to the MGR's mentioned in an earlier post. When did the Wisdom Wheel's appear? Late 60's/early 70's?
Chance came out with Trabant in '62, didn't they? First one I saw was in '64.
By '63 we had skywheels, loop-o-planes, meteor's, bubble bounces, all trailer mounted.