Rod end or Heim Joint questions??

Can someone tell me for sure if there is a suggested install depth with a rod end or if I can install it a few turns into my control arm and run with it?
I would like to have the control arm as long as possible without causing a problem or breaking my control arm.
On a side note, maybe there is a longer one available that I havent seen before or should I buy a set of female rod end and use a threaded stud between it and the control arm.
I have an old ladder bar laying around and I tried to steal the double adjuster from it to use between but it has left handed threads on one side, doh.
I know that I should just lengthen the control arm and live with that but I cannot do that easily right now. The arm is custom and it would be difficult to remake quickly.
Anyhow, hopefully someone else has been in these shoes and can help me.
Thanks, Eric

The rule of thumb is that the threads should be screwed in a minimum of the size/diameter of the rod end. So, a 3/4" rod end should be threaded in at least 3/4", etc.