My Vegas 25.2 had significant leakage on our first trip last fall, but was on the driver's side, originating at the side window, not the slide-out like yours. Dealer found a skip in the seal at the top of that window. No problems found/noticed due to the slide-out.
Either way, I always do a quick inspection of the coach during & after rains. After that leak was found (and carpet soaked), I decided to always have a small dehumidifier and a hygrometer ready to reduce any excessive moisture in the air.
My "room" dehumidifier: "Ivation GDM20 Thermo-Electric Dehumidifier, 1100 Cubic Feet". Not great, but does work.
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