One note about installing the LED's on or around your awning: It is probably worth your time to A) install a dimmer switch and B) make sure the awning lights are isolated from others (like step lighting).
Mine came equipped with an LED strip along the wall just under the awning, and while it is handy, it can be extremely bright. It's great when I'm working on something and need a lot of light, but it's not so great when I just want a little softer light when I'm relaxing outside. Also, the circuit is connected to my step light (little light under the steps for safety), so if I have any lights on, I have to have them all on.
Sorry, can't comment about the vent cover, mine went on just fine with plenty of space.
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!