I, too, am in Missouri (mid-central), and I have had HOSP roost in my regular bluebird boxes a few times, and this is when I set my VanErt in-box trap. I don’t believe you need anything special – they will probably take over anything. We have only had one really cold spell (minus about 4-5 degrees) here so far this year, so maybe it is just not cold enough yet. I know KC is usually a little colder than we are (we are about 70 miles southeast), but I have not had any HOSP roosting this year uet, at least not to my knowledge. They are definitely around, though, as I feed peanut butter suet in my cage feeder, and they usually come around to that (UGH). But sometimes my 7 or 8 bluebirds do chase them off until they have had their fill.