Well, what does it normally rev to pulling onto the trailer? That usually brings most close to the stall speed of the converter, some ramps/approaches are better/worse, so....chances are if You didn't smell anything "hot" or burnt, and the fluid smells normal, You're good.
No confusion about above, when the engine is NOT running, the fluid should check in the "safe" zone or higher COLD. When the engine IS running & trans is in N, the level will be a bit below the "add" mark COLD. When HOT, the levels will be way over "full" not running, & "safe" to "full" idling in N.
