I put the SCRIPTA distro on my RasPi and got it preconfigured as much as I could, but I'm hearing there are issues with chaining large USB hubs together. In other words, if you need more than two hubs you might want to set up another Pi.
The Pi can only handle hubs 2 levels deep. As far as I can tell, the max number of ports at a given level is 7. So, if you have a single level 7 port hub, you can plug 7 into that, and have 49 miners on one Pi USB port. The Pi has 2 USB ports, so, in theory, you can put up to 98 miners on one Pi.