I doubt any bot or human can definitely say what is best here but which game plans are credible and which are junk?

I can tell that you need some practice rolling. You did a lousy job in this position.

Although I am a backgame idiot, here is my take.

Approach #1: Try to divide White's forces so that he crashes. 21/17*/5 might be the play. Under this plan, Blue wants to get hit, so I would not be looking to play safe. The problem is that White has a secure anchor from which he can launch runners whenever he rolls a 6. It may be impossible to force him to crash.

Approach #2: Hit everything in sight, and try to complete your bear-in before White can regain his equilibrium. On this play, that would mean hitting twice, and switching to the 3pt. If White has trouble entering, take a whack at his third blot. This approach may not be right here, but it is not completely crazy. When you find that you cannot prevent an opponent from obtaining the timing he needs for a backgame, so that it is not practicable to make his front position crash, this approach may be your only fallback. With luck, when his shots appear, he will not be ready to hit.

Mike

Approach#2 seems to me counterproductive against a 3-point game. I wouldn't be surprised if black would be the favorite in case white bears off. Your homeboard is easily ruined when throwing some bad double. Most of the time he gets several opportunities to have a double shot at a blot, while he is building his prime. Often he will get a second checker, and even scoring a gammon now and then.

First of all you like to keep the 5-prime, so that black is more likely to kill checkers. Secondly, hitting twice offers black a possible opportunity to recycle an extra checker and a chance to make his 3-point (4-point backgame), and in that case I would double black and doubt whether it will be a take. So indeed I would play 21/17*/5.

It's DMP

For money, I agree that 21/17*/5 looks like the right idea. That would be my over the board play. Keep the 5-prime with 8 of Black's 15 men behind it. You're trying to keep the prime and see if Black rolls some big numbers to spoil his board. It probably won't happen but it's a significant variation to play for.

The 3-point needs to be kep open so you can dump checkers there and perhaps get them recirculated. Any play involving 7/3(2) is really bad because it kills that possibility.

I'd make the same play at DMP. To make the fastest progress in learning the game, you want to learn how to play for money and only much later learn to make adjustments for different match scores. Attaching match scores to all these difficult problems only confuses the learning process.