^^^^ Kids from 2nds and 3rds at "the Big Rugby Schools" would be quite comfortable playing in front of small crowds. To maintain 3 Colts grades across 12 clubs, Sydney Colts annually needs an annual injection of more players than just the chosen ones from the School 1st XV's.
One of the challenges that Colts Club Coaches and Managers face annually is dealing with the wounded and fragile egos of players whose expectations of being the "go to guy" for Colts 1 are greater than their abilities, relative to other players at the club. IMHO former 3rd XV and lower players seem to be a lot more resilient and realistic in this regard.
Not sure that there will be trials on this weekend in Sydney. Most clubs are committed to the Kiama 7's, and go into full on trial mode next weekend.
BrisVegas Premiership trials are already underway. The interesting thing up there is Colts is currently only Under 19's, although under the current regime many kids finish school as 17 year olds. IIRC the current QLD year 8 cohort will be the first group to finish as 18 year olds (typically) in line with NSW. When this group lobs up to Colts in 5 years time, if they haven't already done so, they may need to consider making Qld Colts go to Under 20's to give the players two years post school in Colts, in line with the other competitions.