Illegal forward pass beyond the line to gain

[crimsonace1]

Have a question about illegal forward pass enforcement based on a play I saw a long time ago. 

It's usually 5 yards from spot of foul + loss of down. But usually, it's a QB throwing a pass who's a yard or two beyond the LOS when he throws. 

However, saw a play many, many years ago in a college game - when the option was more prevalent - and am wondering how this would be adjudicated. 

Team has the ball, say, at its own 30, 3rd-and-5. QB keeps and breaks downfield, gaining 15 yards to its 45. Defender closes, so he pitches to the RB. However, the pitch is forward and is caught at the 47. It is correctly flagged for illegal forward pass. 

However, since the line to gain has been achieved ... is it 1st-and-10 from the -40 (which is what I assume),  or is it 2nd-and-10 to account for the loss of down? I'm assuming it's *not* fourth down in this scenario. 

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Now, what if the line to gain had been gained, but the penalty enforcement takes them behind the sticks ... 

So, same scenario. 3rd-and-5 from the -35. QB carries to the 37, then throws an illegal forward pass. Is it 4th-and-3 from the 32 at that point? 

[Bobref]

In both cases you would assess the 5 yd. penalty from the spot of the illegal pass. If, after enforcement, it still leaves the ball beyond the line to gain, it’s a 1st down for A. If enforcement leaves it short of the line to gain, then it’s next down.

[JustRules]

You'll often see officiating documentation say it's not a loss of down, but a loss of the right to repeat the down. But Bobref is correct. If you have achieved the line to gain even after the penalty has been enforced, it will still be first down. Similar to if a team does this during a punt return. You wouldn't start the series 2nd and 10.