Couple thoughts on your tent.
You said you have a lot of natural pests in your area so I would get a intake hepa filter, phresh makes nice ones and keep the tent as sealed up as possible. Get a bigger one than you think you need unless you want to run an intake fan on it or have the walls majorly sucked in. I have an 8" intake filter for my 6" exhaust fan running on medium setting, I need new intake filters now that I think about it and I will probably go up to a 10 for less suction. Also a 6" Fan running at a lower speed will be quieter than a 4".
In tent temps are very dependent on the temp of the room the tent is in (obviously). Its kind of like having two sets of temps to worry about but once you find the right in room temp to keep your tent happy it shouldn't change much. My temps average about 8 - 10 degrees higher than I have my room temp at during lights on, I keep it set at 72 around the clock and it works out nicely for the day and night temps.
One of the skinny line filters that would probably fit above and between the 2 p600s very nicely and not waste much room.
The extra foot you get with the extension is very nice. I can't use it in the new house by an inch and I miss it
