Hi whisperer, exactly my idea.
Make an isolated dark larger box (styrofoam) in which you put your cricket keepers.
Heat the box with a heat mat wrapped around a towel or some sort of buffer so it doesnt touch the cricket keepers.
Make sure the lid closes well and add ventilation holes... check the heat in it, or install a thermostat. done
The darkness and the temperature will make your small ones to grow larger and faster.
Basically it is what I did for all my inverts.. but on a larger scale (for this I needed heat lamps to supply a gradient of temperatures)
Scorpling, sling tray of the big box (middle tray)
It works well