If your shoulder is bad
if the boys will not be around to shovel
if you want a far less "hands on" feed system
Since you already have gone thru all this trouble to make a mighty fine bin and have a great stoker picking fuel out of it
--->Get the 6 foot extension and sell the 4 foot. - set up your bin so you won't have to interact with the coal as much -- sloped floor to the pick up point - rebuild the dog house so you can get at it if it jams
it sounds like if you don't - you may as well have installed a hand feed boiler
I was a teen; standing in my dads 10 ton bin shoveling, from the bin corners, to that darn screw too many nights after school.