construction of all weather turnout area

[twodonkies]

I am looking to construct an all weather turnout area. I am thinking of using stone/gravel for drainage, rolled, membrane, then cushionride on top. The idea is to have a field shelter with all weather section in front, maybe 15m x 20 m, leading onto normal grass paddock, say another 30 m or so. I can use this area for turnout for fatties, lunging? And winter turnout, somewhere dry for neds to stand. It would be for two horses, sometimes three. Is this a good idea, any other suggestions for surface, tips for construction

 

[Goldenstar]

With all weather turnout areas they need a lot of skipping out so you lose surface so that something to bear in mind the cost and ease of topping up.
You don't mention drains you will need to get a digger in and construct drains for it to work really well .