Red Alumalite

Omega-Bond and MaxMetal both come in red. We've done vinyl overlays, and have seen them last around 5 years.

 

yes, the easiest and quickest is to get a piece of red vinyl and cover the substrate if your supplier is that far out for a red panel.
another option is painting but requires knowledge and abilities in the paint to ensure the paint is smooth and uniform.

NOTE; either of these options will leave the backside of the panel "white" unless the red is applied to both sides.​

A 48x96 is going to need a full frame, and with this being a "roof" mount, would also suggest reinforcements

 

have you tried other suppliers? I just ordered a sheet of red max-metal through Grimco and had it in like a day.

EDIT: i just saw "LITE", I assumed ACM

 

The sign will not go on a roof with L brackets no matter what it's made of.

 

And for this type of sign, ACM would do just fine anyway.

 

I have sheeted 4x8s, but at that point just buy a 4x8 print. Or try similar materials from other suppliers as suggested.
I wouldn't even discuss the mounting method with them, I would not want to have any responsibility for it.
When I do installs like that I prefer slotted angle (thru bolted if possible) for a base and then slotted angles behind the sign and angled off the back to that anchoring angle.
I have done shorter ones with hinges on the bottom and angles off the back. But no matter how you do it- it is not an install to cheap out on.