With all this 'hassel' and guess work then not knowing what the images will be like till you get them processed ... sounds like the film camera should be relegated to day-time terra subjects and invest in the trusty 'old' DSLR - I've been out every evening since the weather has 'cleared' at least until the comet makes it's appearance and taken on average around 80 shots per viewing. With immediate feedback adjusting for changing light conditions as you go. Of course there's the post image processing that can take on a life of it's own.
I'm out over Weston Creek, so probably spotted you driving up to Mt Stromolo and sharing the same clouds rolling in as the comet 'comes out'
The DSLR has made a huge difference to astrophotography and it has exploded in the last 10 years or so since the cameras have become relatively cheap. It only takes a few months of practice before you'll be churning out some very professional looking images, that otherwise with film might take several years to achieve similar results. At least with digital your not worried about how much 'film' your using and how much you have left .... Hats off too you if you stick with film and give it a bash ....