Dennis, I personally shoot the area with the Eastwood product you speak of. I like it as it's 'self healing'.
A small wire brush in an extension can snake from both ends to clean it up prior to the Coating.
Then as to the spray shadow you're referring to...
I suggest you start with the bed upside down on saw horses so you can shoot down instead of up.
Second have a strip of cardboard or thin ply cut to easily lay in the corner at a 45* angle to act as a wind dam diverting the 'shadow' further into the roll.
I get those difficult areas covered and dry on a 'set up' day then flip the bed and am good to go for 'paint day'.
