Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[Snapper]

Cutwel had the Gerardi vices on offer in December, I got one. Wish I'd got two. Or thee. Or four

You can set the Gerardi vice up how you want, it doesn't need to have the angle jaws, you can get them with flat jaws, serrated jaws or whatever you want. It's a modular vice and there's a whole tonne of accesories for them. You've still got the issue of the vice bending your work, and in the case of the Gerardi the angle jaws would cause it to bend quite badly (the angle is there to add downforce for pulling the work down to ensure it clamps true repeatedly).

A dedicated fixture really is the way to go here IMO.