I appreciate the information on an overflow for the fresh water tank. Mine is a different unit but I assume they are built similarly.
I have assumed that the fresh water vent, located next to the gravity fill was the vent. It worked that way on a previously owned slide-in pickup camper, where I'd fill the tank until the vent overflowed. Since it was in a small outside compartment with a cover, I didn't care if some leaked out when I started moving it. With the Wildcat, I've waited until I could hear the vent gurgle and stop filling. I didn't want any overflow in the basement. The tank level gauge measures full so that has worked well for me.
I'll check on this if I ever remove the bottom cover.
2015 Wildcat 282 RKX
2011 F350 Lariat, 6.7 L. Diesel, 8 ft., SRW, Reese R20