Rostock Max V2 Onyx heatbed bolt spacer arm

I've been modifying my Rostock Max V2's Onyx heatbed with an aluminum heat spreader above and extra insulation below.

The heat spreader frees us up with respect to how flat the slightly flexible Onyx bed has to be, while the extra insulation necessitates some changes to how the bed attaches to the base. After fiddling around with bolts and washers for half an hour or so, I threw my hands up in the air and said there has to be a better way to do this. Here it is.

These arms are 150mm long