Just explain to him before you leave that you will be gone for two weeks and others will be taking care of him and you will be back, they understand more than what we give them credit for and I doubt he will be mad at you when you get back, quite the opposite, he will be so glad.
It looks to me like you have about all the bases covered, those step by step instructions should be all that is needed to ensure Willis is properly taken care of so now go and enjoy yourself.