I've decided to refurbish some old GW hills, to match my Zama Boards.
My plan is to partially texture them as above, spray them to match the terrain boards, and then add tufts for a bit of variety. The nice thing about these are that they are hollow, and so will sit nicely on top of my very textured Zama boards (which are currently doubling for Mexico, and which will very likely also stand in for Napoleonic Spain). If anyone can suggest where I can get some more (perhaps larger) hollow hills, please do comment below.