You can even use black opaque plexi. There is no need to view the silver bath anyway. Although red will work... why not just block all the light and elinminate the need for a wooden housing at the same time. I have converted a F150 Ford Cargo Van to a rolling darkroom. In the plywood bulkhead I installed a sliding door on each side. One from red plexi and one from black opaque plexi on the opposite side of the bulkhead. Now I can use it for wet plate and film. When working and developing my plates I just slide the red door closed and then when loading film I slide the black door closed also. I can even develop film inside as it is vented with blackout vents and an open vent with a red plexi cover. I Hope to have it up and operational within a few weeks. It has sink and a tank with a 15 gal capacity for distilled water. (it will be filled from the RO system here). And of course a gray water tank. Robert