Hi bluebell,
I’m a newbie to the forum and to PT’s as we’ve only had our 20’x 40′ PT for 6 months- which is 800 sq feet- maybe 6 times the surface area that you are looking at. I’m sure you will get replies from more experienced members here
Nonetheless here’s my two penneth worth…
As much ventilation as possible. That’s hard to automate- unless you have some boffin friends who can rig up a system for you. If you can’t visit often I think that is problematic not just in summer but also in autumn/winter when you don’t want any moist stagnant area rotting your autumn salads. I am opening up every day, even on days like this where the fleeces are on at night.
Here in Wales, the temperatures can rise really high when the clouds part which means an awful lot of adjustment trips. In summer we got frequent peaks of 35’C+
We have wind-up one side ventilation plus doors front and back, we haven’t fitted an extraction fan yet but will do. Even with everything open and some shade netting it can get very hot.
Sliding double doors -essential for us as we are very exposed to wind.
Concreting fixings in? We did – same effort and cost as base plates but then we needed solid fixings due to size, wind factor, high water table with clay pan in places plus high rainfall area.
If you’re not using a water tap nearby gutters connected to large butts as they can fill quickly . Gutters really beneficial even though the rig-up is fiddly with repair tape which channels the rain over the gutter lip. ( Any better suggestions would love to know?)
Non-condensation covers – ours is , still get the odd drip onto the beds but I have no experience with the other cover to compare it with.
Cover tightening – you should be able to do that with a helper at that size, plus online video guides. Ours took four people, a hot day and a lot of sweat and swearing with a subsequent re-tightening from the side rails but, so far, it’s as tight as a drum.
Nicky Kyle’s website is also good for organic, non-commercial PTs – I don’t think she does any hand pollination and it might seduce you to go a little larger if you can.
Overall: expensive but well worth it, even with a second-hand frame like ours.