Ours is done. The trees budded already. yucky syrup.
I am not totally following your hearth design, usually you slope about 30 degrees up from the firebox for the hearth to the chimney. I thought there was a technical reason for it. It was explained to me at one point, but I have forgotten.
If you put fluting in the pan, you will get more surface area, which will speed things up considerably. It isn't -hard- but you do need a big metal brake to do it, and the old copper pans we had, they just soldered them together. They come apart or at least warp if there is nothing in the pans though.
You have to be careful to make sure when you shut it off there is enough sap in the pan to boil off what heat you have left in your bricks or else you will burn it.
It is trickier starting and stopping wood then it is fuel oil.