[CentOS] crypt question/server hotel

I want to put my server in a "server hotel".

But: I don't trust my "server hotel owner".

What can I do?

I can crypt my partition/hdd's that contains the data. Ok. But: then my operating system will not be encrypted. Not Ok.

If I crypt my operating system too, then when a reboot comes, I have to type a password to decrypt. But my server will be at a "server hotel" I can't directly use a keyboard [no service cpu].

What can I do [on technical side] to ensure a little more security to my server [e.g: crypt my partition/slice/whatever, that has the operating system, but without the "type password" ""problem""]

Thank you for any tips/help.