vertical smoke build question

got a question about vertical smoker design. if i wanted to build a vertical sausage smoker out of say a 7' long propane tank with a 30 inch diameter, how much space would i need at the bottom for a fire box? another way to ask my question is how much space should there be between the smoke/heat dissipation plate/drip pan and the bottom of the fire box? is 12" enough clearance? this will be only for sausage so the preferred cook temp would be around 160-165: very low and slow. and also, how close/far away should the sausage be to the plate and drip pan? i've seen a few vertical tank pics but not very much detail or plans on measurements and other technicalities.

thanks!

that is a very nice build! gave me some good ideas that i might borrow. thanks for the link - very helpful.