Hi Naser,
Yes, your approach is correct. You can expose the CRM tables as virtual (SDA) tables in the ECC system and build HANA calc views on the SDA tables. You can also use UNIONs & JOINs as required.
Here is a document, I wrote on heterogeneous report using SDA.
The power of Smart Data Access (SDA) with SAP HANA SP08
Regards
Abani