When you do the clean install, do not give the number when asked. Untick the box for automatic activation. When done, install programs, use it for a while, if happy, activate, then.
After activation, first thing make a system image on an external and update it once a month. If you ever have a problem, you will have an easy back up. No more phone calls, no more installs.
You have 30 days to activate after installation.