That kind of sounds like how clay is supposed to help out defenders against the big hitters.
I think Caro's ideal court conditions would be fast enough to help out her serve and groundies some while being slow enough that she can track down a ton of balls.
There is couple of reasons why clay isn't necessarily a defensive players preferred surface. First one is movement, if you are a defensive player who grew up on hard courts, your movement likely is relatively worse on clay courts relative to hard courts. The biggest issue tends to be changing direction. Movement is probably the one key thing all defensive players rely on, I think on clay courts it's easier to get players like Caro out of position on court, which is obviously not good.
The second key point is weight of shot. You tend to need something, heavy spin, huge power etc. to keep your opponent pinned back as a defensive player. You especially see this with someone like Aga whose shots are lacking in both spin and power, and then on clay court tend to just sit up to be hit. Without weight of shot, your opponent has more time (because of the pace of court, higher bounce etc.) to get in position and probably a higher % attacking shot option.
I tend to think with the way courts are these days, it is a far better option for players to grow up on clay than it is on hard courts. You can translate a clay court game to today's slow hard courts a lot easier than the other way around. I imagine this in part hurts US player development these days, US have a tendency of producing players with a big serve, big forehand, poor backhand (there are exceptions of course) having grown up on fast hard courts, which doesn't translate very well to today's tour. That is probably massively off topic though