5 point harness car seat for tall 3 year old

[PickledLily]

I know 5 point harnesses only generally go up to 18kg, DD is just over 16kg so we have a while yet and she feels too small to go in a 3 point seat.
We don't have a top tether, so can't use the britax advansa, and we tried the reccaro sports hero but her shoulders were almost touching the head rest at its highest setting .

Are there any other options out there?

The diono radian 5 is forward facing harnessed to 25kg so might be worth looking at as I would assume it's a bit taller. Same with the britax two way elite which can be rear or forward facing. The rear facing axkid minikid is taller too.