DO I NEED A PAINT PRIMER IF I AM ONLY DOING A SELECT FEW AREAS OF THE PLANE?

Here are the colors of Coverite fabric and paints I am using for the LT-40.

DARK BLUE
Paint - http://www2.towerhobbies.com/cgi-bin...?&I=LXB310&P=0
Fabric - http://www2.towerhobbies.com/cgi-bin...?&I=LXB189&P=V

WHITE
Paint - http://www2.towerhobbies.com/cgi-bin...?&I=LXB308&P=0
Fabric - http://www2.towerhobbies.com/cgi-bin...?&I=LXB185&P=V

RED FABRIC – no need for paint.
http://www2.towerhobbies.com/cgi-bin...?&I=LXB187&P=M

Requirements for both paint colors says . . .

REQUIRES: 21st Century Primer for a Base Coat.
In order to get a true match between 21st Century Paint and the 21st Century Coverings, you must use 21st Century Primer as a Base Coat.

If I am only doing the engine compartment, fuel tank area, landing gear block, wing saddle area, rear of fuselage where elevator control rod exits, and possibly the tri-stock for fin/stabilizer – and the rest of the plane is done in the pre-painted Coverite fabric – is a Primer really necessary to have the paint and fabric blend perfectly together? Or can I just do a few coats of the paint? I have studied the colors closely and as you can see they are a perfect match.