yes, that is a possible way. Just install a SQL Server 2008 R2 named instance side-by-side to the existing SQL Server 2012 instance and restore the DB there. You then have to change the SAP profile to point to this new SQL Server instance. The parameter for this is
dbs/mss/server=<servername>\<instancename>
e.g.
dbs/mss/server=prdserver\prd
Regards
Clas