Might as well get used to the stuff in a limited fashion before the tanks....
There is no majic to the trailing edge. Some people do not use anything. The rivets do the work.... If you glue it together first and let the sealant cure, it can help make riveting easier and help you keep the edge straight.
Here's how much I put on the angle (both sides) before spreading it out. I didn't have to add any more after spreading with a Popsicle stick (I used a spare pieces of angle, but a Popsicle stick would do the same). http://n999za.files.wordpress.com/2010/03/20100328-017-large.jpg