We just started experiencing this with our present Wrangler ourselves. We have flat towed our previous Jeeps for well over 100k miles combined and behind three different coaches. This Wrangler we have lifted and started experiencing more rock chips on the front than I can live with.
We started hauling the Jeep in our enclosed trailer along with our Harley but for short trips of hop, skip and jump style of trips the trailer can be an inconvenience at best. For this I installed a Roadmaster Tow Defender. We used it a few times last year and I did notice a reduction in chips as well as small rocks or pebbles on the front bumper and cowl area vs. prior to the Tow Defender.
I have a full review and write-up here if you wish to view it.
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27298508.cfmAlso, there are many that will voice the opinion that the mudflap is the issue. It is NOT. This is not my first rodeo and I have had full-width flaps on both previous coaches at the same height from the ground as this one. This coach has less porpoising than the previous as well due to the tag axle. I towed previous Jeeps with the exact setup, I had made no changes to the coach and all ride height inspections are to OEM specs. The change from one Jeep to another was the issue, not the coach.
Mike.