Hey bro your car is looking great!!!
I am doing something very similar other than I am going Turbo B and A Full shave/Tuck
http://www.clubcivic.com/board/showthread.php?t=190266 Here is my "REBUILD" Thread lol.. My car was one direction now I am going a new direction
Anyways, so as far as the Bondo... Whoever told you that is wrong... Bondo can crack yes, however when used PROPERLY it works great... If it ALWAYS cracked why would millions of cars have it on it including brand new cars that get hit?(that may not be the best comparison lol)
Now here is the thing, Bondo should be 1/16 of an in thick at it's thickest point, I have heard 1/8 but 1/16 is much better... It is only meant to be a skim coat, so filling in little weld holes (ie the divets or whatever) and such fine... Fiberglass is also fine, that stuff works well... The only thing I am not digging is filling actual holes that go through the metal... You will have issues with cracking possibly.. or the hole break out... If you can get a welder then weld it up and grind it then fill the holes... Check out my last few pages, it looks very similar lol... Mine has been on hold due to work and just time... But it will get going again VERY soon
Props to you for the work man keep us updated...