The reason the 3-piece thrust bearing in your original post does not have mounting features is that they do not really require mounting. Get one that fits your shaft closely, and it is simply guided by the shaft itself, doesn't need mounting. There is nothing wrong with your original sketch, just need a thrust bearing that fits your shaft. Move the pillowblock bearing up to a high position just under the thrust bearing, as that is where all the side loads will be, and just guide the lower end of the shaft with a loose-fitting bushing.
If you really want a low-profile, lazy-susan type bearing without having a verticle shaft, these ring bearings from McMaster are pretty nice (
http://www.mcmaster.com/#catalog/116/1110/=94ojgg), but may be more than you are wanting to spend