Can be done. A few things for consideration:
Ideally the secondary air would be brought in fairly low... at or below the floor of the firebox, This will help reduce the possibility of smoke / combustion gasses backing up the tubes and coming out into the room.
Secondary air would ideally be exposed to the firebox internals for a good section of the run, and if you can set up a big chamber so the air slows down and spends even longer exposed to the heat, that is even better. This helps super-heat the air. In combination with firebox heating plus heating in the burn tubes, the air can easily be over 1200ºF before jetting out the tubes. If your tubes aren't stainless, this will eventually degrade them and cause 'burnout'. But even generic thin wall stainless seems quite resistant. My tubes are 0.050" wall and see orange-hot heat each season for 15+ years with no notable degradation.
You might look up the pattern / size of holes from an NC30 as some guidance. But ideally, you're punching an 1/8" hole about every linear inch along the burn tube and at an angle where the flame from any given tube jets downward for a bit, but curves back up so the tip of that flame directly hits the burn tube in front of it. This helps magnify the secondary burn effect as each tube helps heat the tube in front of it. I ended up with 4 tubes x ~22 hole each, so depending on the size of your stove and access, that is a lot of drillin' at what seems to be less than ideal body positioning.
As far as air inlets. I was somewhat surprised on my retrofit. Air intake about the size of a quarter seems to be about right. I was prepared for a much larger inlet, but anything more just flushes too much air through, cools the tubes and kills the effect. Thought I recall seeing a couple others use either a 1" or a 3/4" ball valve. So again, in that size range. You certainly won't need a 2 or 3 inch diameter inlet.
It will also be really hard to judge how well it's working if you don't have a glass door. You obviously can't see through a steel door and the moment you open the door to check, it kills any secondary burn.
Not sure how that 'nub' on top of your stove is insulated. As mentioned, my tubes easily glow orange hot, so would likely be something you'd want to protect the surface of the firebox from.
Maybe this is why they call it 'Osage Orange' aka 'Hedge'? Just settling down into a nice 700ºF cruise to warm the house up for the evening. Thought the burn tubes looked nice and pretty orange, so I snapped a photo. The pic really doesn't do justice to actually being here and feeling the...