Sounds like it's condensation and not a leak (be glad for that). Air movement is about the only thing you can do to keep condensation from happening.... air in...air out. Leave a couple windows cracked.
On one of our slide outs, where the floor meets the wall, the wall and floor will be wet. At first I thought it was a leak, but soon realized how wet the windows were, and when simply rubbing my hand over the slide out walls, they were very damp. Enough dampness turns into water droplets. Water droplets collect and form a flowing river eventually.
By simply leaving a couple windows cracked and leave the roof vents cracked a little, we've not had it happen ever again (in 5 years now with the current camper), as long as I remember to crack a window or tow.
Air conditioning inside with heat outside, and heat inside with cold weather outside will both cause condensation. And that water drips somewhere.
Air circulation is your answer. Keep a fan in the cab over.