This is what I was thinking of doing but when I went to Reptile Basics to order just 2 power cords with clips it was going to be only $10 but also $10 to ship. Shipping there feels like a ripoff for something so light and small. I might check other sites to see how they compare.
The tubs are 41qts. I built the rack following these plans http://www.americanmadeexotics.com/41-quart-rack.html
I went with one long flexwatt like I did so that I would only have to worry about one power cord going into one thermostat. I wasn't sure it would be wise to run multiple cords into one thermostat.