Yeah, I agree that Crouton and the like are "cheating" a little bit, and I don't use them personally. I think you're being a little unfair here, though. You want verified boot and a full *NIX offline toolchain. Aren't those incompatible things? Probably the closest thing you can get to local development without cheating is if something like VirtualBox were ported to NaCl, which I don't believe exists, yet.