Rust Proofing

[tallbongo]

Hopefully our Bongo will be back from the Bongo hospital soon with lots of nice new metal bits welded in place of rust.

In order to delay any future visits I intend to give her a thorough rust "prevention" treatment when she comes back. After much research I've decided upon the following treatments. I know you can't stop rust completely but I reckon these will give the best adhesion for the condition of the various areas.

1) Internals (box sections, wheel arches etc) - Dinitrol 3125.
2) Externals (showing some surface rust but seem to be solid enough) - POR 15 anti rust, top coated with POR15 sterling silver.

I've read a lot of posts on the subject and think I have a good idea of how to access most areas including all wheel arches. The van is almost completely stripped out at the rear with only the tailgate and sliding door panels in situ.

I do however have some questions:

1) How much Dinitrol and POR15 am I likely to need?
2) What is the best access to do the inner sills?
3) Other than brakes and alternator are there any areas that I should avoid treating?

Thanks in advance,

David.