My thoughts...
This is technically feasible and I could see myself pulling it off with the right kit. For instance, Dragon's little kit with the anti tank gun and two Fallschirmjager guys, or the Tamiya motorcycle and rider that comes in their King Tiger kit.
Having said that I would venture a guess that we wouldn't see many completions if many entrants due to the time limit. If we opened it up a bit to say a shelf queen that is already 80% done and has been sitting around for a while and you have a weekend to complete it, or maybe even extended it to a month long build, which judging by most builders (myself in the front of the line) is still pushing it with the time constraint.
I do honestly prefer shorter time spans for group builds as I think you can often make them too long. IMO, this in turn gets rid of any kind of 'pressure' (for the lack of a better word) to finish it by a deadline because you think "heck, I have all year to get to that one" and before you know it, that year has passed and after all the initial hype, not many have actually completed it.
I'm not completely dismissing this idea but would make sense to tweak it a little?