If* it were an A/C condensate drain line leak it would be plentiful - how much water are we talking about, a wet smudge or pints of water? Is it one, ten or fifty drips-a-minute?
Can you place a catchment to say it's leaked a tablespoon an hour or a pint an hour?
Also with a line leak there would be puddling hidden above where you're discovering it - some trailer shifting or rocking with stabilizer jacks raised up off the ground would likely increase the flow for a few minutes. Any sign of that, or is the flow undisturbed?