Depending on whether my assumptions about your setup are correct there is actually a way to handle this in SSIS that works quite well and may save you what sounds like a boatload of work you are thinking you need to do. I setup a test package with a Bulk Insert Task as follows to mirror my most basic impression of what you're doing to load data, with a couple tweaks, namely the addition of an Execute SQL Task before the Bulk Insert Task and a property change on the OLE DB connection object:

If you set the SQL statement of the Execute SQL Task as

SET DATEFORMAT DMY;

then because the OLE DB Connection object has its RetainSameConnection property set to True the Bulk Insert Task will also be subject to the SET option executed by the Execute SQL Task. The RetainSameConnection property is not something a lot of people find a need for, but it allows us to unpaint ourselves out of corners that Microsoft seemingly has painted us into from time to time.