well you could run a single heater in each plate, it might take a bit to warm up but no prob with that. you'll use a cartridge heater like this https://www.amazon.com/YXQ-Cartridge-Electric-Heating-Fittings/dp/B06XWB86GF/ but you can choose how powerful it is.

i'd probably do dual heaters in the plate for an 8x10, that's decently large. depending on the inkbird you get, you don't need two controllers, just a controller that will run two or four heaters, which is no prob if you want them set at same temp. if different, then yeah you'll need two controllers. they're very cheap.