We have been carrying our bikes on the front of the truck for 4 years. This arrangement has worked very well. Our current setup uses a Swagman bike rack that carries the bikes on their wheels. This way they do not shift and the different frame styles do not cause and issue. The first year we had a rack that hung the bikes from their crossbar. This was a pain sine the bikes kept shifting with the wind and my wife's bike had the one wheel close to the ground. The Swagman solved both those issues.
I have not had any indication of airflow problems.
We have used this on trips to Atlantic Coast, Florida, Pacific Coast and now in TX near New Mexico border. Many miles
2012 Chev 4x4 Crew Cab 5.3l 3.42 trailer package
2011 Jayco Select 28U
gone 2003 Chev 4x4 5.3 Extended cab
gone 1991 Award Classic 30