Unlock all prob cores at once? Or with similar sized parts?

[CiberX15]

The problem I'm trying to solve is I want to use a probe core to turn a staged launch boster around and fly it back into a suborbital trajectory. But the probe cores are almost always too small to do that. Unless I'm missing something, the probe cores aren't actually any better the bigger they get, and if you can build a 1m wide computer that can fly a ship, its weird that it takes an exponential amount of research to do that with an even larger computer?

So my request would be for the probes to either unlock all at once (minus maybe the stayputnik which is kind of a tutorial probe and presumably intentionally unwieldy), or in tandem with the larger parts so you can always build probes to scale with the size of your rockets.

[Superfluous J]

I put them in a cargo bay or something else structural.

[The Aziz]

They have stronger reaction wheels, can hold more electricity, and probably something else.