Have been a diesel engine RV owner for almost 25 years and have never seen or heard anybody using something to block the intake of air to radiator during winter time. One could do this but most RVers head south so they don't need to be concerned about over cooling the engine. One thing comes to mind and that would be not to forget to take the blockage from the front of radiator when weather warms up. Sure could do it but don't thing anybody will.
Tom/Teri 16031 NKK 117995 FMCA
18 London Aire 4531 Spartan K-3 605
97-04 LA 04-18 Essex 2018 London Aire