You can use a coinjoin like method to submit all values of multiple validators in one transaction.
But then you need to have some type of an online off-chain protocol that creates the coinjoin transaction - correct? So it seems to be consensus problem by itself if you want to do it in a decentralized manner.
I guess you can do coinjoin in a contract, but it will require a lot of steps. So using an online off-chain protocol seems to be the most efficient way.