Terrapin, I have the same oven.  From what you describe I owuld move it further from the fire and a bit higher.
I have found that it works best when the middle of the oven is about even with the middle of the flames, to gauge tempature I think that I want to be able ot hold my hand in front of the oven for 5 seconds before having to move it away.  

I have also found that the type of fire that works best is one that has more flames than coals, which is diferent from a normal cooking fire.
Therefore, I usually try to bake deserts, cook dinner first, then build up the fire.  Put dessert on and then tend the fire while eating dinner.  After dinner is done and relaxing around waiting for a warm desert...a bit of whiskey...now you made me sad that I am not getting to BW this year.  
Hope this helps, pm me if you have more questions, although my response may take awhile...I am traveling...as usual.