Paint and Surface Area

Greetings folks,

Seeking a quicker easier method to find surface area, #1is my current method as I am attempting to find the surface area of an engine case:

1. I created a shrinkwrap of the engine case. I used auto hole fill as these surfaces will be unpainted and used with gaskets. I then use analysis, model, mass properties to calculate surface area of the engine case but I have to go back and find the area of each gasket surface to subtract from this initial, overall surface area.

Another attempted method:

2. I have also created a shell of the exterior surfaces of the engine case (also utilizing shrinkwrap) and attempted to utilize analysis, model, mass properties to see if it could calculate the surface area as previous but, due to the surfaces theorectical, infinite thinness...there is no density and no area although graphically represented. What did work was using analysis, measure, area but I would have to click on each feature/entity and add each measurement. Although this provides me with a highly accurate surface measurement.....time consuming as every feature must be accounted for.

Method 2 would be ideal if I could select the entire shrinkwrap created shell, and then select all surfaces (then merely divide by 2 to discount the interior surface) but I cannot figure out how to include all features....holding down control will not work using analysis, measure, area.

Anyone care to suggest a quicker yet accurate method?