Get there early and focus roughly while it's light out. Use some tilt to get the foreground and stars in focus once you can see some, which may sound obvious but is harder said than done depending on the geometry of the object...especially as I'd suggest shooting at the widest aperture possible or close to it.

I once shot some Provia at f/11 for like 6 hours and got literally nothing on the film. I was using a 2x center filter though which was dumb. So I think at f/16 you'd be already pushing it, so I'd shoot for f/8 or wider.

HP5 would be a big no-no I think. T-Max 100 or 400, or Delta 100 for sure would result in more actual exposure.