I'd like to reproduce a very interesting photo that I took digitally.

It requires 5-7 separate exposures of about 30 seconds each. I quite laboriously combined them in PS when I shot it with my DSLR. Now I'd like to do the same thing with my 4x5 using multiple exposures on a single sheet film.

I have oodles of Velvia 100F lying around, and I think it would work very well for this kind of shot. But we're talking about a total exposure time of 3-5 minutes. So calculating exposure will be tricky, and I worry that I'll run into color shifts.

Do you think this is reasonable to try with Velvia 100F, or is there a better film for this purpose? And how will I calculate the exposure -- if I plan on, say, 8 exposures, do I just meter in Tv mode for 4 minutes and divide it into 8 separate shots?