We had a similar issue camping on the September long weekend in Waterton Lakes NP. It was a Bangladeshi monsoon for the first couple of nights and we had this mysterious leak coming in from under the fridge
area. Once I got home and starting investigating (and after drying out and several hot showers), I was looking at the fridge
vent covers as well.
I ended up re-sealing the upper with putty tape, and around the belly band area where it had shrunk away from the cover. I didn't know (or think about) the foam tape, but that may be next years project. I added some extra screws too as I wasn't getting good bite on several.
I did a minor re-seal on the lower removable cover, but honestly wasn't imagining how the water was getting in there, so your photos are very helpful Michael.
Any improvement will have to wait until next year, as we have tucked the Bigfoot away back into indoor storage for the winter. Hoping next summer I don't have to camp in a monsoon again, but we shall see....