yes that size smokehouse imho would allow "mingling smoke & rapid exit"
That bubble stuff sucks ar$e from a genuine insulative standpoint, lot of smoke & mirrors where the numbers are concerned.
Better off with a foil (not paper) backed pir insulation board such as xtratherm, the thicker the better, insulation is nigh on equivilent to double the thickness in fibreglass equivilent. tried & tested, easy to cut, easy to overboard, easy to dig out "just enough" to make corrections as you go along whilst maintaining a good thermal envelope, & a squirty can to fill any gaps afterwards, or off-cuts with some aluminium tape!
It's good stuff, cheap & versatile.
The pull of the artisan for me is the easier cleaning due to size compared to the regular unit, but as per my thread it takes (ish) 3.5 times more material to fill it with unless you bend in place a restrictor (easy enough)
The other thing about the pir panels, cut some 1-2mm steel panels in place & glue them onto the backboard & you up the interior walls integrity when it comes to hanging racks off it as well as giving something for the smoke to adhere to & build up against.
OSB is good & cheap but not designed to get wet.
If you google bbq spares you'll see a plethora of thin smoke stack pipes & the like IF you find the aesthetics of plumbing type polypipe not to your liking.
Alternatively (though sweaty) a cheap option is to obtain a naff plastic garden storage box stick it upright, cut & polyweld some pre-measured polypipe internally (screwfix, t bends & straight sections) plus a few outside to shore it up against high winds & then frame around it (screws in exterior pipes).
These garden storage things are modern tat & not really fit for purpose, but can obviously frame out something with any cracked panels fixed & filled with some pir cut to shape to spread the load...
free-cycle or look out for a deal at the likes of B&Q if you want a temporary outdoor unit whilst you get up to speed..
(powerwash & bleach clean)
Sticky aluminium tape, (thermal,PIR grade @about £5 a go will seal a lot of nasty air gaps.
If the other half gives you grief about fridge space for your "product", again free-cycle is your friend!