The plot is often least important part of a film (or book), and would be pretty easy to structure to tell the entire story in a couple hours.
Genocide by the Cylons kicks in within the first 30 minutes, after we've been introduced to everyone and their situations. Spend the next 60 to 80 minutes with the humans desperately escaping/fighting the Cylons. End with a denouement that resolves the Cylon situation (peace or extinction) and lands the humans on Earth. Roll credits.
If not that, then trilogies are all the rage, in which case the first film can be about the initial attack and the ragtag fleet's escape, with hints that the Cylons are still in pursuit. Second film would probably be a great opportunity to tell the Pegasus story, which is really one of the best stories in the BSG mythos. Third movie can be the quest for Earth.
Plotting this stuff out isn't that hard. It's writing all the beats, drawing memorable characters, and pacing each scene well that will make or break it, and then you have directing, acting, and effects to worry about, any of which can ruin what was otherwise a good script.
Just have some imagination about it. Yes, you can tell BSG's story in a 2 hour movie, it just won't be exactly the same story you got before.