I agree with the rolling on the first couple coats to fill the pinholes.  I did a couple other things and had no problems with pinholes.  I scuffed the surface with 80 grit and really blew off the surface, up close, making sure to get the dust out of the weave.  I rolled on a heavy coat of primer and then used a Bondo squeegee to press the primer down into the skin.  I then re-rolled the primer to smooth it out.

 

After the initial rolling of a couple coats, you should spray on any additional coats.  The stipple of the roller will create thin spots in the primer and you won't get much "net" buildup in the low spots.

 

Mike Easley

Colorado Springs