Welcome, Roman! Nice find, and so glad your wife is now on board! These little trailers do clean up well!
From what I know of U-Hauls, I would want to check for window leaks
fairly soon. Use a spray nozzle on a garden hose and angle down from above. Leaks
usually show up on the floor under the window. Given the condition of the interior of this one, you may be just fine, but it seems to be a common problem with U-Hauls.