Hi Nicole - No matter what spoilboard you use when you cut holes in your job you are going to loss vacuum. What you need to do is cut a groove in the board and place a gasket it in so the gasket isolates the vacuum when it breaks thru. If they are repeat parts then you make custom aluminium, pads that have an o ring in them. You have a problem with size as they are small parts so have a small air pressure on them. If they are one off parts then you need to think about serial clamping. This means the part is clamped and you have to put a program stop in so you can release a clamp , place a clamp and keep going. But I think a custom vac mount is what you need. This can be as simple as a thin rubber sheet or as complex as an o-ring designed thingy depending on part numbers. If they are one offs and being thin and small double sided tape is the go to solution.
Another strategy I use is to clamp the plate or sheet down on a thick spoil board then cut the holes first. Then screw through the holes and then cut the profiles (remove the clamps if needed to, but you do need to hold the "rest" of the material as when it comes free it can move around spoiling your work! Sometimes I add holes to parts just for this purpose. May not be possible in your part. But you need at least two holes in a part to hold it properly. You can also break your "rest" cutting into stages so each bit can be removed by hand as it happens. Cheers Peter
rereading your note I think these are nameplates so they will have two holes in them. I'd go the drill holes first, screw it down, do rest path.