I understand you want to validate the domain with Office 365. Also, you don’t want to influence the production site to Office 365.
It will be no influence on validating the domain in Office 365. The verification is the activity to prove domain ownership. Normally, we use MX record value and TXT record value to verify domain.
After domain verification, customer requires to add different DNS record to make Office 365 function works.
For such information, you can refer to http://office.microsoft.com/en-in/office365-suite-help/use-a-sharepoint-online-public-website-on-a-custom-domain-together-with-other-services-HA102895890.aspx?CTT=5&origin=HA102851067 and http://office.microsoft.com/en-in/office365-suite-help/create-dns-records-at-any-dns-hosting-provider-for-office-365-HA103479204.aspx.
Thanks,
Jim