About the only way you'll be able to light them up from behind is if they (Winnebago) actually "cut" the panel with the wording and laid in or over an opaque cover that could be "lit" from behind, thus shinning light through the cuts. I've changed most of my interior lighting to LEDs, including the aisle lights, and the one that's on the opposite door side of that switch panel.
Now, that light is now considerably brighter than the cheap-o festoon bulb that was in there but, not bright enough to light up the switch labels from across the doorway. This is just a suggestion but, if yours are like like mine, in the fact of what switch does what, in the order from the top down, then all you have to do is remember the top two switches. The top one on mine is the "Lounge lights" for lighting up the front end of the coach and, the second switch down is the porch/step/front aisle light/grab handle lights.
Now, this of course is surmising that you don't need to do a lot more than light up the porch area or, the front end of the coach in the dark for entrance or exit.
Now, just in case you do find that it (the panel) was actually set up for interior lighting, you've got a couple of ways to approach this neat little project. One, find an LED light strip at your local auto parts store or, Walmart, (they got all kinds of junk like that in the auto section) or, you could do what I did on the switch lighting on my 145,000 mile Honda Goldwing 1500, and that is, purchase some 3mm LEDs, solder them in series 'till you get at least 6 or 7 in a row and attach them to the back of the switch panel with hot glue. Since there's no heat emanating from those bulbs, the hot glue will work just fine without chance of heating the glue and dislodging the wiring you just did.
Now, just in case you're wondering why the 6 or 7 in a row, LEDs can only operate on about 2-3 Volts DC or they'll burn up. So, you have to add a series of them in a line to be able to accept the 12V power you'll be applying to them.
There's one more suggestion I might make. www.superbrightleds.com
has a number of types of LED lights, including very small licence plate lights with LEDs in them that you could mount to the side of that switch panel with a small piece of plastic or aluminum angle and it would only show light on that panel, switches and writing. Just some thoughts here.