On these cars with the available parts you’d have to work pretty hard to run “too much” caster.
It is possible in general though. The more positive caster you add the more the wheels camber when your turn. That’s actually what adds the steering effort, as you turn the wheels thr positive caster actually adds negative camber, which turns the wheel more on its edge, which literally lifts the car. So, you can run so much caster that the turn in camber change will be too much and the lifting effect can actually unsettle the car in a corner.
And there is a point where you have too much camber gain too, what you’re trying to do is have the outside wheel flat on the ground so you have the best traction. The camber gain counters the body roll and CG change, so ideally you want the camber gain to match the lean angle. Too much can also reduce traction.
But that’s the theoretical side, the reality of the parts available is you’d have a hard time adding so much caster that you’d unsettle the car or have too much camber gain.
