When I moved into this house way back when, I collected some cardboard boxes and then flattened them out and pinned them to my garage wall. I then took some A4 paper boxes and cut them so I would have a right angle shelf which was then pinned to the other flattened boxes. These were mounted about shoulder high which gave me plenty of freedom to spray horizontal as well as from above and below. With figures I usually rotate them four times to get at them from four positions. Them being mounted on milk bottle tops makes it easy to move.
I recently had a skip in to clear my section so took the opportunity to throw away the cardboard which had a large amount of overspray on. This had the desired result of protecting the GIB board (dry wall). I then set about replacing the spraying area. Luckily I had a sheet of slightly damaged ply left over from building which went onto the wall. I then mounted a piece of timber on some spare shelf brackets that I had stored away. The centre support sticks out a bit longer which gives me a hole to hang items from. I'm pretty happy with the setup as it is a lot more sturdy than before and looks a lot cleaner (at this stage).
As you can see I am undercoating a whole regiment of Zulus at one go as the shelf is long enough to allow this. I will then base-coat these with a can of brown top-coat which worked out well with my last regiment.