Just a question or two.

It looks to me like the drain holes that carry water away from the front windscreen are just in front of the hood (bonnet) hinges. Wouldn't having a Rust Prevention shop put one of their flexible wands down in there and spraying the bejeesus out of that area help the rot issue in the '02/3 cars? Also drilling your own drain holes just fwd of the jacking points.

Do the front turn signal 'repeater' lights just forward of the front doors also give you access to the 'A' pillars, or just the outside of them?

 

The water flows into the grill in the plastic cover at the base of the wind shield (cabin air filter cover). It then enters the A pillar (you have to remove the cover to see where the water goes). You can spray down into the opening but there are several layers of sheet metal that might make thorough coverage hard to do. Also these are ten year old cars and the rust doesn't show quickly so the damage may be largely done already.