I would either setup a localhost and test there, or setup a subdomain to your main domain. You can do a clean install, or do what @lesley said to do and clone your site, then copy the RC1 files over it. The more people testing RC1, or latest source, the better. More bug reports from different people will help the developers troubleshoot and repair issues faster, which will result in a faster release. If anyone needs more detailed instructions or help do this, let me know, and I'll try and help.