So I finally got the new fan from the seller and it worked without issues. 

However, I wasn't getting anywhere near the 29/33dB claimed on the label. On the lowest setting, it was 56dB from 3m away and 60dB from 1m and that was with the filter and air duct installed. I got 56dB on the last one before it broke and I thought it was that loud because the duct wasn't on. 

I asked the seller about this and they don't know how the manufacturer is testing this either. I know that manufacturers stretch the truth (such as laser diode sellers saying that a 5.5W output power laser is "40W") but I'm an entire 20dB out. The seller was kind enough to send me a 1m acoustic ducting, which is just what I needed to get air from the window all the way to the tent.

Now I've been getting some actual work done in here:

The noise floor is 45dB without the fan and still 56dB in here, though the dominant frequency is a low white noise, with the inline fan sounding like a vacuum cleaner in another room. I haven't smelled any car fumes from the road outside the window, and the air is cold like its been air conditioned. Along with the views, it makes me feel like I'm in an (underground) datacentre (or a fridge).

From feeling the air on the exhaust vent, I'm glad that I went with the 6 inch fan system. Speed 1 is probably the lowest I would've been okay with, and sometimes I enable the high speed to get more air going though. The actual noise output is almost the same, but the fan frequency is higher so it's more audiable.

Right now, the TrueTent TempLab has become a not-so-temporary TempLab. I should've seen this comming, but honestly I'm so swamped with workload that my itenerary is essentially:

1. Wake up and make breakfast
2. Work for 24 block-minutes
3. Eat
4. [more of step 2 and 3]
5. Sleep

So I might as well save the 2 hours of transit time.

[1 April]  It honestly feels like air conditioning in here, almost like I'm actually in a datacenter (I hear they're cold to keep the server thermals down). I've got just the background track for this: