Not able to control start date in Create Expense item page (Per Diem)

Problem: There is requirement to control "Start Date" when employee creates expense item in Travel & Expense page. But employee can select start date older than 10 days which violates the business requirement. I found this document [How To Restrict Users From Submitting Expense Reports That Are Older Than 30 Days? ( Doc ID 2323066.1 )] but that does not stops employee from entering past Per Diem due expenses.

This is significant business requirement that start date in Per Diem Expense item must be not be older than 10days and as I checked there is perhaps no setup/ profile/ lookup to control this and it looks like very concerned issue.