We use an inkbird controller as well. Our temp probe is located in the skimmer chamber & we have 4 heaters in the return chamber. The temp holds between 79 & 80 degF. We ran a second temp prob in one of the overflow chambers of the display for 3 months to ensure the temp is evenly distributed across the system.
I would avoid a heater in the first chamber (upstream of the temp prob) as that might not give you a reliable indiciation of what is happening in the display.