Don't really need one for that small of a tent. I got exact setup almost and I just open the intake flap with the screen on it. Usually in the bottom on backside. Then vent out the top with my carbon filter outside of it. It will pull in enough fresh air without a fan, just have to ensure the...
I found it easier to just put a bucket of rock salt in the tent, no need for holes or a lid or a seperate bucket to catch water. The salt absorbs the moisture all you have to do is stir it around once in a while and when it clumps together into one big solid piece and can't be broke up no more...