I agree, stop rewarding the behavior. It may be difficult at first and he is still going to be capable of waking you guys up but ignore the meowing, don't even get out of bed until you need to or until the cat is quiet.

I have siamese and oriental shorthairs (different color class of the siamese) who are world renowned for being extremely vocal. Not only do they meow a lot but they are loud and sound like a baby screaming/crying. So I feel your pain, but trust me. Ignoring the cat will work wonders.

If you go for the squirt bottle, stay at the door. Don't spray and go back to bed - stay right at the door so you can catch him immediately and he doesn't hear you moving around. Even moving around, getting out of bed, can be rewarding as the cat knows you will open the door. A delayed spray will delay the effect of the method - but if you stay there and as soon as he opens his mouth you open the door, spray, and shut the door, he will learn that all he gets when the door opens is water, and it comes fast.

I only use the ignore method, but I crate train my cats like I crate train puppies. If I didn't I would likely use the squirt bottle more often.