Hello Michal,
good question, I have never tried it before. I don't know if the connection methods with r3load work without the default sapschemas and SAP NW tables. You have to try it out by yourself.
Another method is to export the schema in BIN mode. It depends on the size of the DB if this is a workable methode.
With SLES12 both architectures are on little endian and a backup/restore should work.
Regards,
Jens