KNIFE EDGE 
LOL!!!
I like to use Expanding Ultimate Glue for this step... what it does is pushes the root cap against the fuse ever so slightly for that perfect joint fit of wing to fuse!!! The wing bolts are lightly installed just to counter the expanding action of the glue. Same for the stab root caps!!!
It's a simple job afterwards to sand the slightly larger root cap and fillet of Ultimate Glue
