Oh... ok, I thought there was a strange way, but utxos are inputs for the transaction, so I have to know and to sign they. You meant that it's not necessary to import a priv key and build a set of available utxos but I knew already that.
I mean that you can transfer this part of work to somebody else.
There are hundreds of persons who already have the set of unspent outputs.
Why not to use their work instead?