Here you're defining syntax around your orthographic definition of what a word is.
> "Is he really, in your opinion, to see her tomorrow?"
The opinion words "really" and "in your opinion" added into that syntactic structure parallel the manner that opinion word "bloody" is added into a lexical structure to become "abso-bloody-lutely".
No, I'm not. As I said, there is no unit in English (regardless of whether or not it is written as a single word) that both behaves like a verb and has a distinct future form.
>The opinion words "really" and "in your opinion" added into that syntactic structure parallel the manner that opinion word "bloody" is added into a lexical structure to become "abso-bloody-lutely".
You seem to have missed that fact that even if you remove "really" and "in your opinion", the unit you identified as a verb is still broken up in the example I gave. In "Is he to see her tomorrow?", "is-to-see" is not a contiguous unit. Although the idea of treating the subject pronoun as a verbal infix might be charming (English as Mohawk!), the subject could be a much larger phrase, as in e.g. "Is the man in the red hat to see her tomorrow?"
It is simply not true that adjunction of adverbials has the same properties as expletive infixation. Even if there is some loose analogy between these two processes, I fail to see how it's relevant to units defined in terms of a single "beat in speaking".
You can insert stuff between "is" and "to-see" (and between "to" and "see", I hope you agree) because English mostly parses into left-branching trees, which is the only reason why you can't insert stuff between "see" and "-ing". Natural languages don't liberally mix left-branching structures and right-branching ones because they're hard for people to understand. E.g. Pinker's "The rapidity that the motion that the wing that the hummingbird has has has is remarkable" is grammatically correct but not easily understandable. The contiguity or lack of it operates on a different conceptual plane to whether a "word" can be inflected or not.
> loose analogy
To take some example language from your reply, some people speak this as two words, others (e.g. some Americans) as a compound word. Because the concept of a word is not well defined, the boundary between morphology and syntax is blurred. Putting "is" and "to" noncontiguously before a verb is the same as putting "-ed" after a verb. They are both "inflections".
It's clearly thousands of miles away from being a generally accepted analysis of English syntax. So unless you've written up your analysis in detail somewhere, there's not much further to discuss.