Need to Create Supports Where it Won't Let Me

So, I have a piece of stock bolted down in the Keepout Regions shown in the picture. The bolts need a clearance of 10mm so I have that set in my retract height. For the sake of rapid production, I cannot bolt the material in another place. Let’s just assume that.

How can I set supports inside this space? I want to create supports that go into the keepout region, since that area won’t be machined and I know that the piece can be anchored to it, I don’t see why I shouldn’t be able to. Problem is that MeshCam only allows me to construct supports for the outer region of the piece.

How do I get around this? And I’m hoping the solution isn’t to literally create them in Rhino (the modeling software I’m currently using) and then somehow create a keepout region around that. Because that would take too long on each individual piece.