I added them to my MAC 208. Not really for the water on the bottom of the camper, but more the road grime that covered the rear stabilizers after a few trips. This helped a lot in keeping that off of them.
I purchased the mud flaps on Amazon, cut them to the right height, and then bolted them to the frame. What you can see here is the ends of the three bolts with ny-lok nuts on them (stainless hardware). Between the frame Channel section is a piece of pressure treated wood to use as blocking and the mud flap.
You can see a photo here at my blog:
The Schaffer's RV Trip Log: Finally! Spring is here!
Otherwise, the photo is huge on this site for some reason.