Hi Bob, just a thought, when I lived in Somerset near Cheddar, the local strawberry growers had a brilliant system which maybe you could adapt for your chillies. Its hard to describe but I'll give it a go. get some metal tubes bent into hoops similar to those on a polytunnel but obviously smaller, and heres the clever bit, they used baler twine to tension the plastic by having shorter hoops of baler twine to the side of the metal ones (actually tied to the metal hoops) by doing this, they could slide the plastic up either during the day or in hot weather and slide it down again easily when needed (slide the sides to the middle thus exposing the plants) its also possible because the plastic is being tensioned by the twine, to only slide it halfway up if needed!! Ive copied and used this system when covering beds of pyracantha, cotoneaster and any plants that needed winter protection when i worked on a huge container plant nursery in Pinneberg ( i was suprised that these needed protection there ??) and I made them about 6ft wide by 3ft high with the hoops about 6ft apart, is this big enough for your chillies ??
just a thought, regards, Lannerman