i have a smoker much the same size. i have been thru a few different smoke gens and ended up doing the mailbox mod BUT used a cheap turkey roaster cause there are no mail boxes here ... LOL
so i started with 1
AMNPS then 2 and only lite 1 end. this gives me smoke all night (when they stay lit) for when im doing a pulled pork. i now have 2 12"
AMNTS welded together . was sometimes hit and miss if the
AMNPS would always stay lit, seemed to crap out in the middle of a smoke sometimes.
these tube smokers just smoke and smoke and smoke. TONS OF SMOKE TOO !!!!!
so i only fill up 1/2 the volume but full length and have not had a problem. uses more pellets than the
AMNPS and can get about 8 hrs from it. ya will get longer from the
AMNPS but 8 hrs seems good enough for me to run with and if i miss a bit of time before reload thats ok.
you will find ya never have too many AMNPS /
AMNTS laying around cause they are good in the grill also.
Goliath