I can help you with this. We owned a 02 Adventurer 35U before the current DP. I hooked my passenger wheel well cover on a short post when I was navigating thru a tight campground and paying attention to where the left front was going and not where the right rear was headed. It was at nite so I can always use that as a partial excuse. I tore the plastic wheel well panel and also marred the storage compartment door in front of it. I had to remove them both. Had to replace the wheel well panel and take the door off to get them both painted. The wheel well panel you will get from Winnebago will be black in color when you get it. They will provide you with the paint code for the correct color match. I paid about 210 for the panel when I bought it about 8 years ago. The paint job for both ran about 400.
To remove the panel I had to remove the long rail immediately above it. You start from the back of the vehicle and remove the end tab and then slide the rail out of the long slot. This will reveal the system of attachment tabs underneath the entire rail for all of the doors as well as the panel you need to change. It is a Phillips screwdriver, no special toolling required. Since you lost your panel with the tabs attached, you may need to get new attach tabs with your panel if they don't come attached when you pick it up. They may be molded into the plastic. Do you have remanants of plastic tabs with phillips screws directly above the wheel well panel that is missing. I don't remember. There will also be three or four Philips screws inside the wheel well opening that hold the bottom ends of the panel.
This was not a really difficult maintenance task. I got the low down on how to do it from a body shop guy at the Winnie dealer in Tacoma, WA. It was just as he said it would be. It took me about an hour to take it apart, then about 45 min to put it back together. A call to Winnebago service should provide you with the same result.
Good Luck with your project. Your "loss story" is better and less embarassing than mine was. Mark In Palmer, AK
OBTW: We luv the diesel bus we got when we sold the Adventurer after 10 years of great service.