Warren Gatland’s side are looking to end an eight-match international losing streak that stretches back nine months.
Wainwright, Williams and Thomas accounted for more than half the caps in the Wales starting side for the first match of the series.
“I think you trust the squad,” said Howley.
“We’ve picked them to come here and give them an experience of Test match rugby.
“If one of them is unfortunate not to be available for selection, we back whoever will step in.
“Over the period of time in the Six Nations, we’ve made changes. Self-belief and confidence is huge when there’s a lack of experience because of age.
“At 22 or 23, you give them that opportunity to go out and perform.
“There’s a balance, but hopefully the players are available and we have a consistent selection because it’s a short tour.”