Thrust races are ok as are angular contact ( expensive solution) I tend to use taper rollers to support the weight and keep things centred ( which ball thrust bearings won,t do easily).

On the only machine I have fitted with a full set of slip rings I used taper rollers top and bottom but the lack of frictional damping makes it rather inclined to wag around in turbulent winds.

I agree with something to take the vertical thrust and tend to use a taper roller at the top, the rest is sort of pipe on pipe but with a plastic or Tufnol ( Resin bonded linen) bush at the bottom end although most of this comes from my engineering background, as long as you keep grease in there plain pipe on pipe will last for many tears.

With any form of ball or roller bearing in these set ups it will work as long as you keep grease in and water out. If the thing starts to rust it will be no better than a steel plate sitting on the end of a pipe and may fail sooner.