I am planing my trailer smoker build and it will be a reverse flow design. I am at the scrounging stage and am now looking for the material that is used for the reverse flow at the bottom of the cooker, what thickness is ideal for this? And what can you get by with at a minimum? Anyone know the girth of the 250 gal tanks? Right now I have a 120 gal tank that is nearly 8 feet around but am changing gears now and am going with a 250 and am wondering if the girth will be similar in size.