Your plan sounds like a good one. I really don't want to invest any more in the smoker I'm using now, so I put an oven temp. on the grate, ran a few test burns to get the temp at the grill reading. When I got to the temp I wanted after a few times and knew where the cheapo guage on the hood was going to be, I took a Red "Sharpie" pen and marked the hood guage where 225( at the grate) was, that way I know where the temps are without opening the hood.
Weber "Q", Weber Performer, Weber 22.5" Bar-B-Kettle