So you are just talking about doing it straight out sketchup? Or are you using rendering software to add shadows and smooth out your animation?
I haven't experimented with moving objects in SU, but I've done animations of spinning around a building at about 3000x2000 resolution for maybe 3 minutes for projects at work. I took quite a bit of time, and I used a rendering farm to do it. I also had the help of a $4000 pc. I'd totally do some cool stuff on it if I had the time, but at the end of week I just want to get out of the office.
Good luck though. I really don't think your idea is bad at all, definitely workable if you give it some patience. If it's just a quick animation (maybe 20 seconds at most), it should be doable. Just let your computer chug away at it for a couple of days. (depending on what PC you have) Keep in mind, because it's an animation, you really shouldn't overkill on rendering settings.