For exhaust any 4in in-line fan will do, in such small spaces just a strong enough exhaust can can create enough air movement. Your tents probably 40 maybe 50cuft, 4in exhaust fans mostly pull 190cfm so you’ll have total air exchange like 4 times a minute.
2.3 feet? Meters?
Any fan that will fit will work.
Large amounts of air moving slowly works best.
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