Not really difficult, just different. Actually, PP/PS tubs may be easier for you to control than glass, or melamine. You should tailor your setup based upon the actual environmental conditions where you live, and the temperature at which you keep the room(s) that your reptiles are in: how well it's insulated, reliable HVAC, weather conditions (what happens if the power goes out, will they overheat, or get too cold?) .
With rack designs that are more open (Freedom Breeder, ARS, Fusion, Animal Plastics economy line) you'll want consistent room temps in the high 70's to 80 degrees.
Enclosed racks (Animal Plastics, RBI) hold heat better, and are more suited to maintaining cool side temps in rooms that are kept at lower temperatures, or the temperature fluctuates.
Either design can be suplemented with a low wattage flexwatt on the cool end, controlled by a separate thermostat (or one thermostat with multiple probes).