Scramble Rule
 

Can the QB scramble if he is totally behind the LOS when the board is turned off and all eligible receivers are engaged?

NO
 

QB is only allowed to scramble (angle and/or adjust) if there is an eligible receiver.

Ok.

So, can the QB scramble if he is totally behind the LOS when the board is turned off and there is at least one eligible receiver?

THE WAY IT READS
 

...is ONLY if the QB is on or across the LOS. If he's sitting in the pocket 10yds deep, can't scramble. That would be the ONLY play people ran if the QB Scramble were allowed on every play without restriction(s).

In the HHEFL, we have a unique way of allowing that to happen (or not happen):

The QB can scramble on any and every play if there is at least one eligible receiver, BUT the ultimate equalizer is ALL unengaged Defenders, plus those that are engaged on the Offense's side of the LOS are allowed to angle/adjust toward the QB!!! How ya like them apples?

Please re-read the rules in part G of Plays from scrimmage. If your QB is on an immobile base in the pocket, and the conditions listed are met, you can scramble.

I read it to say that if he is on a stationary base, and has not crossed the line of scrimmage nor has he vibrated more than 15 yards behind the LOS, and there is at least ONE eligible receiver, then you can scramble by replacing the player/base and can angle and adjust. The non-engaged defensive players can then be adjusted.

Update: Nodave on the Miggle Boards confirms no "tuck and run" for the QB.