Ventilation for cattle panel greenhouse

Hay everyone hoping to get a little help here . Never had or messed with green houses but my wife really wanted one and she showed me some videos about making them with cattle panels and since they were about the same as some chicken tractors I build said why not. Added some little solar powder fans for a ventilation system and they help , it's definitely better then when we were trying. To use it without them,but with the way our weather fluctuates ( south Mississippi is bipolar as hell one day it's 40° next its 80° ) it's been a little rough. So looking at adding one of those auto venting deals but wasn't sure what would be the best route. I see most green houses will vent from the roof but can't really do that with this one too easy. Figured I could just add like a window deal to th back under the fans with an auto opener but don't know if having it too low would cause issues. And where it's at from the house I can't run powder to it for a big vent fan so yeah.
Anyone with one of these styles got any tips or advice for venting? Other then just leaveothe door open lol