Combining ECC tables, non-SAP tables in Universe Designer

Hello -

We have a need to join specific ECC tables and non-SAP tables (complex); hence, thinking of Universe Designer.

Reporting is via Crystal, but because of the complex nature of the joins, we are eliminating the ECC connector option for Crystal.

We understand that there is a ECC ABAP connector still in prototype phase, and not for productive use; hence, eliminated

We would prefer not to bring data into BW physically, or virtually.

Having said this, is there any other option for joining ECC and

Ex. Connecting to ECC at the Oracle DB level : Is this advisable.

Thanks

-abhi