Sentential Subjects: vP?, TP? other?

I've just completed a preliminary draft of the introduction to the section on topicalization. Exactly what this involves theoretically is huge question: for now, I'm adopting a fairly unconstrained interpretation of the term to mean any fronting of a constituent to the initial specifier position of the clause, where the fronted constituent is typically followed by the "topic marker" thì (but also by what I'll call secondary topicalization markers including mà and là (in certain uses). Hence topicalization will include relatives, conditionals and a bunch of other things besides] But the present query relates to sentential subjects, which I also think are topicalized in this sense.

First the text:

Sentential Subjects

One type of topicalization that is of particular theoretical interest involves sentential subjects. As the examples in (3) illustrate, Vietnamese sentential subjects are not introduced by any subordinating complementizer: indeed, it is ungrammatical to place a complementizer in sentence-initial position. In spite of this, such constructions are highly frequent, and appear to be parsed without difficulty:

3a. (*Rằng) họ cười khúc khích làm chúng em thẹn. (Nguyễn 1997: 222)
that prn laugh giggle make plural prn embarrassed
'(The fact that) they giggled embarrassed us.'

b. (*Rằng) nhà tôi ở trong hữm thế này mà anh tìm ra kể giỏi lắm. [Huffman: 277]
that house I be in alley like this REL you find show skillful very
'(The fact that) my house is in an alley like this yet you found it shows that you are pretty clever.'

The examples in (4b) and (5), in which a clausal argument precedes the assertion morpheme có and the anterior marker đã, respectively, are also consistent with a fronting analysis as sentential subject-fronting analysis: see Duffield in prep. and sections NN above

4a. Ông Ba có ngủ ngon không? (Dương 1971)
prn Ba asr sleep well Q
'Did Mr Ba sleep well?'

b. Ông Ba ngủ có ngon không?
prn Ba sleep asr well Q
'Did Mr Ba have a good sleep?' (lit. Mr. Ba sleeps is good, not?)

5. Họ ăn đã xong. [G: 258]
prn eat ant finish
'They finished eating.

Now, the query. I'd like to be able to distinguish a number of analytic options for the bracketed constituents in (4b) and (5). The minimal assumption is that they're something smaller than TPs, say vP, for the sake of argument. However, if it's possible to have higher functional categories (sẽ đã có không) within this constituent then we d be forced to assume they're tps at least. [Note that although there lot of structure in (3b), it's all fairly deeply embedded and still compatible with a vp=sentential subject analysis.] Any thoughts, help, advice, most welcome!