I am wanting to add Matrix rainforest 2400x600 fencing extension to my existing fence that is 1200 high, I am not allowed to fix it to the existing fence so am planning on using Whites 240cm posts, my questions are:- would these posts be suitable? what screws would be best to use to attach the posts to the extensions and should I use concrete around the posts? The videos about installation assume that it is being attached to the fence. I am in W.A. so the soil is sandy.