Probably an idiot question, but just wondering. Can you SVA a car with just a deflector and then add a proper screen later?

Yes, but it's best to SVA it with nothing at all. That's what I did.

David

Yes, is the answer. As long as the deflector is not in the line of sight.

So you don't need demister or wipers

Agreed - no screen of any kind for SVA (to avoid potential problems with radiuses, etc.), then fit whatever you decide afterwards

thas what i'm gonna do! am i right in thinking that MOT only requires a wiper on the drivers side? doesn't seem right but i'm sure that what i've heard. the truck is built with a place for the wiper over towards the drivers side, but where it is, if it sweeps 180 degrees, it won't reach the other side of the window

Leave the deflector off too.
It's only another collection of sharp edges

Ditto. No aeroscreen or anything for SVA. Decided I wanted to fit a proper screen a few days afterwards...

Thanks for the answers guys, looks like the easiest way to go!