We have the car guard shield and like it very much, gives the car a lot of protection. When we went to Alaska, I towed my 1/2 ton truck and made a front shield with plywood, to protect the front of the truck, again horror stories, it worked so good I should have painted it to make it look nice. Anyway we had our M/H with mud flaps, and full rear flap that was about 3 or 4 inches off the pavement, no problem with big stones or anything else. We did get a 3" round smash in our windshield before we even got to Alaska, log truck, and two cracks in Montana on the way home so Alaska isn't as bad as some of the stories going around. We also got some heavy material from Walmart and went across the windshield and tucked in into the doors to hold the cloth.
This is what we did and worked out fine for us.
Have a great time on your trip.
Bill