I'd assume that an "off the board" check isn't made until AFTER a ship has completed its maneuver so this is academic but if a ship will overlap the edge of the board AND another ship does it get to move back off the overlapping ship and save itself from going over the edge? Assuming of course that the final position isn't also off the board.

I'm wondering it this would be a possible way to "rescue" a high value ship from flying away assuming you have some way to get a blocker in there.

Don't overthink it. What is the ships final position? Is it off the board? Remove it.

So yes, you could strategically place a blocker to prevent the ship from ending its maneuver off the board.

Q: Can overlapping other ships cause the active ship to flee the battlefield? A: Yes. If any part of the ship’s base in its final position (after moving backward) is outside the play area, then the ship has fled the battlefield.

Yes, provided that your blocker was not off the edge of the play area to begin with (he would be removed immediately at the end of his movement otherwise so wouldn't be there to overlap) and the overlap movement forces your ship back far enough that no part of the ship was over the edge.

A very risky proposition but would be highly circumstantial to pull off.

The answers are what I expected so thanks.

I know it's a risky proposition but certainly could be an aid for someone who wants to keep an opponent from "escorting" an ionized ship right off the edge.