Summer temperatures and pepper fruit set - time for fleece?

I know there have been a few threads about this recently but on reading through and finding this:-

I wanted to ask for a bit more advice from those with more experience than me.

My minimum overnight temperature on the North side of the poly is still only about
12C - obviously, I don't know how long the tunnel is at this temperature for but it's well below the level for good fruit set on my peppers (they are in the middle bed so should be slightly warmer) and I'm having the whole flower drop experience. Although the petals are falling and leaving what looks like a potential fruit they are not nearly as big/full looking as the ones that have actually set so I am assuming poor/no fertilization.

I am misting round the plants, which Joyce Russell recommends (I know they are self fertilizing but my tunnel can have quite a dry atmophere) and there are insects in there most of the time as well.

My question as per the title is, if you were me would you be fleecing the peppers up at night to try and trap warm air for longer? (Day temps are high teens upwards.)

Thanks in advance people.

(Tomatoes are doing ok only the odd flower dropping.)