First, are you doing full backups all of the time? If so, have you thought doing one full one a week and differentials during the week? Have you looked at backing up by file group? There are also products like...
SQL Server Backup & Recovery Solutions | Dell Software
I have not been a production DBA in a long time, but trying to slap the query governor on your VERY important backup and maintenance jobs is not the right answer.
You may also want to look at how you are rebuilding your indices. There are several options there that might be more suitable to your needs.
If one brings so much courage to this world the world has to kill them or break them, so of course it kills them. The world breaks every one and afterward many are strong at the broken places. But those that will not break it kills. It kills the very good and the very gentle and the very brave impartially. If you are none of these you can be sure it will kill you too but there will be no special hurry. Earnest Hemingway, A Farewell To Arms.