if smell is important to avoid, then you want to make sure you have negative pressure. you want it on the exhaust and wehther it's at teh start of that duct or the end depends on the filter. some are not reversible. follow instructions. usually you suck in through the filter, so you'd want it on the inside in that case. if it is reversible you usually have to flip something around and then it would work fine outside -- the negative pressure will ensure all the air goes through the filter.
if you don't have negative pressure you will get leaks and odor escapting. it doesn't have to be extreme negative pressure. i'd dial it down until it just barely pulls in on walls.
if smell is no concern, fuck the filter, lol. i'd go with a little positive pressure becuase then you don't lose 4-6" of space all the away around the middle. if that is a problem, can cut some bamboo stakes or something cheap to prevent bowing of tent walls.