bags on bars

i have a forward triangular 4 link and i just had a couple questions about bags on bars. does it matter which bars you put it on, the top links or the bottom links? what is the best place to mount them, the middle of the bar, front of the bar, or the rear of the bar? also on an adjustable 4 link, does it matter how much of the threaded rod is inside? will it make it weak if theres in inch inside and like an inch and a half outside? sorry for all the typing. thanx.