Upgrading 500mm X-Carve to longer 1000mm x 500mm

I’m considering making my workspace longer…adding 1000mm rails for the X-axis. So here’s my list:

-2 x 1000mm Makerslide
-2 x 1000mm x 20mm x 20mm extrusion
-custom wasteboard
-longer wiring

Should I be adding in another cross support in the middle (along the Y-axis)? If I mount the wasteboard in well I imagine this should provide enough rigidity?

Drag chain, at least one extrusion, but more if wasteboard flatness is important over time, and hardware for mounting the extrusion (s).