The good news about crappie in a 3/4 acre pond is this...when they finally overpopulate (which they will..it's not a matter of "if" as much as "when"), a 3/4 acre pond is easy to fix. You can fix it in one day, and not break your back pocket.
I don't recommend crappie in small ponds either, but if someone wants to try something different, I'll go with them, as long as they know the consequences.
Who told the Wright Brothers they couldn't fly?
Here's facts..a summary of everyone's posts. Crappie are top line predators, limited only by mouth size. They spawn first during the season. Crappie are unpredictable spawners, may not spawn every year. Baby crappie eat everything they can, especially newly hatched bass, bluegill, bugs, etc. Bass eat crappie, if bass are big enough. Crappie like deeper water, with fairly dense cover.
You make the call, but I don't like crappie in water less than 20 acres, especially if managing for bass.
Surprisingly, there's very little out there regarding research of crappie population dynamics.

Teach a man to grow fish...
He can teach to catch fish...