Here is the setup I ended up with.

The uprights fixed to the wall are stainless steel C rail which we use at work to mount pipe clamps to. The model supports are pieces of 15mm OD tubing which have had an 8mm bolt swaged into the end using our hydraulic hose crimping machine. a nut and washer are fitted to the bolt before it is swaged in. This is used to clamp the support in the desired position on the rail.

The wing rack is two pieces of C rail notched, bent at right angles and welded. These are fixed to the wall and used with more pieces of tubing as wing spacers.

Totally over engineered but works well and can be expanded easily - Job Done!

Malcom