Number of trusses?

I dig out my borders like JJB, water into pots and take all leaves off below the first truss. I do get blight but it’s generally late in the year, October normally when everything is dying back anyway.

That's what i do as well topping the border up with dalek compost then when my toms have finally finished I plant lettuce and chard to eat over winter. 
Mines only a 8x6 so I do keep the door and back louvre  open, roofs on a autovent hopefully all that through air helps.