After some consideration and with the kind advice given by people commenting in my earlier post on the subject, I have decided to change around the format of my two-module sequence, combining the two modules into a single, two-part mega-module. I'm estimating the page count at about 100 pages, although since I am still filling in details of the encounter areas in the second part, I might be off in that estimate. It's hard to tell at this stage.
Hopefully the module will be completed some time in middle to late October -- the biggest potential delay is the playtesting phase, since it can sometimes take playtesters a week or more before their gaming groups actually get together to try the module out. I'm pretty fast at making any necessary revisions from that point onward, though.
As I continue fleshing out the details, I'm getting happier and happier with the way it is turning out. My only concern at this point is to avoid having too many moving parts at any given time for the Referee to juggle. There are a lot of moving parts, strange things, and weird conditions interacting in the second part of the mega-module, and it's important for the sake of playability to keep too many of these from being involved all at one time.
I'll keep people posted if anything particularly interesting happens as I continue writing. Otherwise, it's just typetypetypetype from this point onward.