As stated many times on this site, that's not a necessity of the 40/25.
I live in a state where we use *no* visible play clocks, not even when a field has them.
I am a huge proponent of the 40/25. Officials will get used to it quickly, and quite frankly, I've seen so many variations in the pace of play from one R to another when watching games I'm not working (I'm an R and I am a proponent of "get it down and blow the whistle") that it would add a layer of consistency that is sorely lacking around here. We can't be the only ones where this is the case.
As far as manipulating the RFP (and therefore the play clock) in blow-outs, etc., I doubt that we're ever really taking more than 40 seconds between plays anyway and it's a small price to pay to have consistency across the board.
I really think this would *improve the game* and I'd really like to see the committee look at this and other timing rules -- I wouldn't want to see them alter these rules every season, but it's been about 20 years since the last major timing change and it does feel like it's time.
(FWIW, I would never run the game clock after incomplete passes. No other level does that and we can recover quite a bit of time by simply starting the clock when the ball is spotted after plays that go out of bounds outside of 2 minutes. And with the 40 starting immediately after an INC, crews will get a ball and get it down quicker, IMO.)