How hash with salt, or could I push data exceeded size of scriptSig.

[xqyww123]

It's a usual purpose, but I didn't find any approach to hash with salt. So I got this strange idea. Is the following script valid?

sigScript: OP_PUSHDATA1 <number 30, means size> <first 20 bytes data>
sigPubKey: <remain 10 bytes data, as salt> OP_SIZE  30  OP_EQUALVERIFY  OP_HASH160  <hash>  OP_EQUALVERIFY

It's really really strange, pushing data exceeded sigScript, though it indeed make sense.

Or, any better way to hash with salt?