For my Ford, I used small tie wraps to secure pieces of ordinary window screen to recesses in my grill. It worked well for me for years. They collected lots of bugs so I know they did their job. Never had an issue with overheating.
Sherm & Terry w/rescues Steve (std Poodle) & Eydie (min Schnauzer)
2015 Jay Flight 27RLS (Camped: 102 nights 2015, 90 nights 2016)
2006 Ford F350 6.0 PSD, Lariat, 4WD, CC, LB, SRW, auto., Camper pkg.