Mike, you may be able to get away with just removing the rear seat providing once you do that you are able to assess how easy it will be to remove any residual moisture. If you find any water, the aggressive use of a wet/dry vac will speed the drying process. You be the judge of how wet it is when you pull the rear seat. If it's really wet, I would go ahead and remove the front seat and remove the carpet and really get it dry. There is nothing worse than the smell of moldy, wet carpet. It never goes away.
1987 BMW 325