Get the leaks fixed. Could be fairly simple. If the underbelly is wrapped then ask for it to be removed and see if the insulation is wet. Let it dry out if so and replace the insulation. Lots of TT/5ers leak for various reasons. Doesn't make it right. But it happens. I don't think you have a lemon. Just go spend some time on different brand forums. You'll see all makes, models of different price points with leaks. Most of the time it's nothing more than a seal that's defective or maybe put on wrong.
Yeah it sucks that a brand new RV has to go back to the dealer to get fixed. Just part of the game IMO.
What's sad about all this is that once anyone gets their current RV all moded out and whatever warranty things fixed then you almost don't want to get another because you could end up with something worse.
On top of that they depreciate like there's no tomorrow.