Ken, On our 2004 Marquis I had the entire front cap exposed from the interior of the coach to install a new swing up TV.
Inside the front cap there was nothing other than one length of R-13 fiberglass batt at 15" wide. This is the full extent of what was in our front cap. Now the front cap is 27" in length from lower side where the windshield fits into it to the top area of the cap where it joins the flat roof structure. Construction in the front cap is only a fiberglass shell and is nothing like the flat roof areas.
Monaco saved some nickles with the 15" in a 27" cavity. Absolutely worthless.
One thing to check is the clearance lights as we found all of ours cracked and this is most likely where the water was or is coming in as these lights are not sealed on the interior side. In replacing clearance lights we used LED units. After getting all the clearance lights installed we taped over the wire connections and then we used a foam kit that you can buy at any box store, which comes with a 6' length of hose and multiple spray tips, and we insulated the entire front cap with this spray foam at about 2-3 inch thickness. The foam in these kits is a closed cell foam and at 2" thickness it is a vapor barrier, ie it will not let water penetrate thru it. It also made a very significant positive impact on the wind noise as well as staying warm in cold weather and keeping heat out during summer.
The foam kits run around $345.00 at most any box store. Menards, Home Depot, Lowes. You can also use them more than one time as you change out the spray nozzle and can spray again in a day or week or month using the remaining contents in the kit. This foam works great in many other areas under the coach to silence the road noise.