I need to unburden myself of this possible solution or I won't be able to sleep.

Player must have nothing but Blackjacks.

Dealer must start with a possible Blackjack.

Anything else leads to a non-fixed total number of cards.

Assuming BJs win 1.5 units even after splits:

Then following 2 splits (of Aces), 4BJs win +6 units.

Add a LOST insurance bet for -0.5 units.

Total = +5.5 units (which is pretty rare - and hopefully unique).

= $137.5 (for $25 units)

8 Player cards (4 x A,10)

2 Dealer cards = Ace 1st, then a non-10

..

Now, if they could only stop rehearsals of the Texas Chainsaw Massacre outside my window, I might be able to get on with my life.