the only potential issue I see is what if the ball lands out of bounds. we would have to 'guess' where it left the field of play. Like a punt very tough.
Not true Derick...
For the purpose of this rule, where it crosses the sideline is not considered, rather did it cross the LOS in flight is all that matters.
Again, for the purpose of this rule, the LOS extends OOB to infinity, and all the legal forward pass need do, is cross the LOS in flight.
While they likely don't word it the same way i am, the requirement's are the same for NCAA and NFL. This is why when the result is the pass is it lands in the stands and it is ruled legal.
(Ralph has addressed some concern that passers may be intentionally aiming for the Prom Queens Mom)
Also, just a legal is when the pass, inflight, crosses the down box, in front of it or behind it.
I hope what I just described makes sense?