Downgrading issues in MPP from 2010 to 2007

Recently one of my colleague has developed a schedule in MS Project 2010, sent it to customer in response to a RFP.
But the customer reverted saying that they are unable to open it MSP 2007.

When he tried saving in Project 2007 format, he faced data loss with tampered schedule due to manual scheduled tasks in 2010.

So how to get rid of this issue?

My approach to tackle this issue is:
1. Select (filter) the tasks which are 'Manually scheduled'
2. Copy the Start and Finish Dates into temporary fields Start1 and Finish1 columns
3. Change the 'Schedule Mode' to 'Auto scheduled' by selecting all 'Manually Scheduled' tasks
4. Copy the values from Start1 and Finish1 to Start and Finish columns
5. Save the mpp in Project 2007 format