You cannot use that 1 thermostat for both your UTH and rack if that is what you are asking.
You can however use just 1 thermostat for your rack as long you are using a uniform amount of heat tape (flexwatt) for each row. (If you have any questions about installing the flexwatt you can check out www.reptilebasics.com/flexwatt-faq.html)
Just a recommendation but I highly recommend getting the Herpstat for controlling the temperature of a entire rack.
I think that cheap amazon one may be fine for use with a UTH but I personally would not trust such a cheap thermostat for an entire rack. The Herpstat can handle 500 watt which is more than enough for your rack so you can plug all your rows in it. Also it is reasonably priced.
If you want one cheaper than the herpstat I would recommend the Ranco Theromstat you can get at www.reptilebasics.com/thermostats/
If you have any thermostat questions you can check out www.reptilebasics.com/thermostat-faq.html for some good info.