I don't think 見るからに is usually used to describe yourself. 一目見て is its synonym and might be easier to understand. 見るからに means as soon as you take a look at something/someone else, you get some impression about it/them. So, you already know you are lonely or well, and can't have a visual impression about yourself. If you'd like to use it to describe yourself, it would be a little tricky. For example, you can say, 'Did you get the impression I'm lonely?' In that case, your third sentence can be: 僕は見るからに寂しそうでしょう？