We're headed down the highway towing a Wrangler Jeep. We sort of looked at a shield in front of the toad to protect it, but couldn't find one we liked. The only one that looked like it would work and was easy to mount, couldn't be mounted on our MH because the exhaust would have melted it. It's a 2002 jeep with 140K miles on it, so a few more rock chips won't rally be noticed if they happen. The rock shield was going to be a little over $200 and a new windshield for the jeep is less than that.
I have heard (but never actually talked to them) of people who have the large single flap also on the back of their MH, having it removed because when HM goes over rougher roads that often has pavement breaks, the flap hits the pavement kicking up loose rocks onto the toad.
And for those towing a Wrangler, look at these.
Jeep Lexan Headlight ClickyI much prefer H4 lights over sealed beams and being Lexan they'll stand up to a flipped rock a lot better than a glass headlight. I put them in our jeep last week. A non-working headlight from a flipped rock was more of a worry than anything else.
Bill