I agree with the liquid calorie idea to a degree. Where it concerns juice or juiced things where you have taken out the part of the nutrients that help make you feel full (ie. the fiber). But in the case of a smoothie, I honestly don't see how it is any different than cooking it as far as how quickly your body consumes the calories and nutrients. And for me the liquid does make me feel full, of course my smoothie ends up being the full blender container, and 48 oz of anything even water is going to make you feel full. And the ingredients in my smoothie ensure I stay full for at least 4 hours. Plus many of the same people who tell you that you won't feel full if you drink your calories are the same people who will tell you to drink a glass of water before a meal so you will feel full.
But smoothies are definitely a personal preference type of thing, and since I know I won't eat breakfast, they are a fantastic way for me to get my protein and veggies in in the morning. The hubs and the kids think I am crazy though.
The egg whites will help you with the calorie/protein ratio, excellent start! I think you are just going to have to not use any extras (ie mayo, salad dressing, oils, full fat dairy, etc) and use the highest protein with the lowest calories (ie. the old stand bys...tuna, chicken, turkey, egg whites, etc)
I am more of a chai spice tea kind of girl, but that does sound really good! I actually found a high quality orange flavoring I could add a drop or two to my chai spice and get a similar effect. Yummy!