As i was doing a careful check for any possible water infiltration issues, I remembered that I had not ever checked the two clearance lights that are recessed into the top of the front cap. What I found did not please me. After removing the amber lens, I removed the screws - which were rusted and therefore showed some amount of water leakage. When I removed the base, I saw that the seal was a thin foam gasket:
Here is the rather artful picture my camera took as it struck the ground after being dropped from the ladder I was standing on:
I checked the camera and it survived the fall. Then I cleaned up the recess in the cap, applied butyl tape to the back of the base of the light, and reinstalled the light. Hopefully my butyl tape will seal better than Jayco's flimsy foam gasket.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch