That looks good.
I filled in those plastic vents as they let a lot of water in, which then sits and rusts away the steel frame where you can't see it. Luckily, I got to that in time, not like the wreck I've got out the back where you can see the rust got out of control.
You might want to check out the top tailgates in England to see if they work out to be cheaper, but at the end of the day you may as well just get the job over with.

