So instead of re painting my entire mast, I could strip all paint, buff it and leave it as is? Where fitting contact the mast, I would use proper isolation between mast and fitting to reduce corrosion.The inside of the mast is open to the air. Water, salt, and air are okay. The surfaces under fittings don't get enough air. Good primer, paint and some sealants keep the water and salt away while reducing electrolysis from the different metals.
Alloy aluminum used in masts is quite resistant to seawater if left bare and open to the air.
Booms usually break at the vang attach point because of the (foolish) use of stainless fittings by many rig builders. That wrap around spreader attachment is not one of the good ideas for longevity. Pretty and shiny though heavy, corrosion prone and complicated.
Stainless backing plates are also a terrible idea. Use alloy.