The chief priests did not go looking for Judas. According to scripture Judas "Went to the chief priests". Judas went looking for this. According to scripture Judas was a thief. He stole from the money purse the apostles had.
As for stacking the deck, yes, the chief priests according to scripture went to the wives of the men in power and told them to tell their husbands to have Jesus crucified. Greed got the better of Judas. I often thought maybe Judas hated Jesus for the cheap lifestyle the apostles lived in. I think Judas even hated the poor. In scripture Judas yells at the woman who anointed Jesus with the expensive spikenard. Judas said this could have been sold and given to the poor. Scripture says, "He said this not because he cared for the poor but because he was a thief" and stole money from the purse he carried for the apostles.
Judas was actively seeking an opportunity to betray Jesus. Scripture says from then on he looked for an opportunity to betray Jesus.
Although Judas being able to find Jesus alone was one reason Judas was who betrayed Jesus, Judas was also able to identify Jesus. At the Garden of Gethsemane Judas identified Jesus by kissing Him. Jesus says, "Dost thou betray me with a kiss?"
The chief priests wanted to get Jesus alone because the chief priests did not want to incite a riot. In one scenario the Passover was coming up. In another set of circumstances Matthew 21:46 "But when they sought to lay hands on Him they feared the multitude."
Another reason why Judas was the one to betray Jesus was the person who betrayed Jesus had to be willing to betray Him. At the last supper the apostles asked, "Who would do such a thing?" Judas would. The other 11 apostles knew where Jesus would be also but they did not want to betray Jesus.
Why get Jesus alone? Even if not a crowd, Peter was an excellent swordsman and he smote the high priest's servant's ear off for seizing Jesus.
The priests did not need someone who could get close to Jesus without Jesus realizing what would happen. Jesus knew who and what would happen when He picked the 12 apostles. In scripture Jesus says picked the 12 apostles Himself and still there is a devil. At the wedding at Cana Jesus says, "My hour has not come." At the Last Supper Jesus announces one of you will betray me. Jesus says it is he who dips with me. When Judas asks, "Master, is it I?", Jesus answers, "You say." Jesus tells Judas at the Last Supper do it fast. At the Garden of Gethsemane Jesus BEGS the Father to take the cup away from Him. Jesus says do you not think I cannot ask my Father to send angels to help me? Jesus also says, "But how then will the prophesy be fulfilled?" Jesus knew what was coming. He did not need to do anything special. He could have simply not gone to the Garden of Gethsemane. Jesus even pushed His own capture. In the Garden of Gethsemane when the crowd still cannot identify Jesus despite Judas kissing Him, Jesus says, "I AM WHO ye seek."