Advice for long exposure over bright city

I'm hoping to get out early tomorrow morning for a sighting of the ISS and STS-131 as it passes over Jacksonville, FL. I have a pretty good location in mind, but I will be shooting the trails from the two orbiters with the downtown buildings in the foreground. I know a typical shot could be 30-60s at f/8-11 and ISO100/200 without blowing the highlights, but I have no idea how to do a 5-10 minute exposure without blowing everything out.

I have a shutter cord, so length is not an issue. Just exposure. I have a CPol I could use, if you think it would help.

Any advice? Break up the path? Go for it?

You could always take two shots: first get the city exposed nicely, then do the long exposure and combine them in post. Otherwise I don't know.. maybe a graduated ND?

Matt, thanks for the response. I had considered doing one long exposure like you suggested, but I'm afraid of the sky blowing out. My other thought was taking multiple 30s shots, one after the other.

Looks like I'm going to have to wait to try those theories out, though, as the ISS isn't passing over again for a few weeks.