I hadn’t realised that folks used toaster ovens to actually toast things like bread, bagels, etc.
While it doesn’t do a perfect bagel toast I use a Dualit for all toasting duties. I couldn’t figure out why folks, and hospitals-which is where I first came across them, bought these until I got one. I had been used to pop-up automatic toasters at home. Revelation: the Dualit offers greater control and keeps the toast warm as it doesn’t throw it out from between the heat source.
I see the new generation has a one-side toasting option that would do perfect bagel toasting. Polished 4 Slice Toaster | The Original 4 Slot NewGen From Dualit
The APO might be overkill for toasting a bagel. But it is awesome for everything I have tried with it so far.
As for 4" clearance, if I remember correctly that is for stacking. 3", 4" is there that much difference? if there’s good air movement I’d expect it should be fine.