Luna, I know you're experienced and know the cladding needs lots of prep before painting, but take a look at this Isuzu bulletin. It shows what needs to be done depending on what brand products you use.

Cladding Refinish Procedures-Part 1

Cladding Refinish Procedures-Part 2

Cladding Refinish Procedures-Part 3

Cladding Refinish Procedures-Part 4

Cladding Refinish Procedures-Part 5

Mark