The Silkie will likely need more time, though I don't have experience with them, as their feathering makes it harder to hold in heat compared to regular feathered birds. Continue working on weaning them off heat, and for now I'd hold off on moving them out until they feather in a bit more and...
I'd fully wean them off heat first - they shouldn't have it during the day at all if you're planning for them to stay out overnight, when it's cooler. At least 2 of the chicks are still a bit sparse on feathering IMO for dealing with 40F full time.
Rats are absolutely a problem and have been...