I think our best bet would be to have the vacuum sort of roam freely in an arc on the bottom of the carriage, just like the cannon does at top. The vacuum is the new lowest layer.
The crane is the closest part to the front so far. The "cranechain" part is on the bottom, followed by the "craneclaw" parts, then the "cranehand," and finally the "cranearm" is closest to the viewer.
Here is the vacuum. The segment at top is the part that connects to the chassis; the one at the bottom is the vacuum head. I made three slightly different connecting parts which you can make the neck out of- it'll probably take 7 or 8 of 'em.
This is my last part for the evening, I'm afraid; I'll put up another part tomorrow though.