Why not replace your thermostat with the stock replacement? It sounds possible and likely that yours is either stuck closed or partially stuck closed. I just replaced the t-stat on my 2014 as it was partially stuck open and would never allow the coolant to come up to full operating temp. If you replace the t-stat with one lower than the stock unit and don't have a tuner you'll likely throw an error code for the coolant not reaching expected operating temperature and the engine won't fully warm up to the level the computer expects. If you replace it with a colder t-stat and then adjust the ECU with a programmer, what do you have to gain there?
Teams of engineers with a combined knowledge set far beyond yours designed the systems and components of these engines to run reliably and efficiently with the stock components. If one of the operating parameters such as coolant temp is out of expected range, there's likely a problem with that part, not the selection of that part by FCA, except in rare cases. AKA, just replace the thermostat with the factory $30 unit and call it a day.
