Basic Rules are there to set the ethics as much as they can be set. Additional rules may be set to prevent other "behaviors".
One example is to shoot out much of the ammo to lighten the airplane. Another is to climb above the hard ceiling and dive to the agreed to altitude for the E advantage. Some guys will want to start a lead turn prior to the actual physical merge. If you suspect this may be the case, be specific on the rules prior to the fight. I've dueled guys who thought nothing of cheating. More often, I've dueled guys for whom cheating was never even a thought.
When two guys have great respect for each other and value fairness above winning, no rules are required as neither will attempt to gain an advantage outside the scope of fair competition.
I've fought many duels where my opponent pulled off to reset a merge realizing he had an advantage. I do the same, although I really don't mind starting at a disadvantage under certain circumstances with certain individuals. If I'm dueling a guy who is in the learning process, I'll give the advantage just to see what he does with it.
Most guys are honorable, a few are not. Film usually exposes these few to public scrutiny.
My regards,
Widewing